FOOTNOTES:
[A] This MS. work was never intended for publication, and therefore was not written with care.—C. D. 1858.
[B] I can see no more difficulty in this, than in the planter improving his varieties of the cotton plant.—C. D. 1858.
Contributions to the Anatomy and Natural History of the Cetacea. By R. Knox, Esq., M.D., F.R.S.E. Communicated by the Secretary.
[Received Oct. 6, 1857.]
Part I. The Dolphins.
The dissection of the Cetacea, and more especially of the larger kinds, is attended with great difficulty, and not unfrequently entails heavy expenses on those who attempt it. For these reasons I have thought that zoologists might be pleased to have, even now, submitted to them the results of numerous dissections made many years ago, when, not stinted in means, and having the aid of excellent assistants, I attempted the dissection even of the gigantic Arctic Rorqual, the largest, perhaps, of all living beings. Certain of the details have been from time to time laid before the public, but in an extremely scattered and incomplete form, and without the illustrations (artistic), which explain so much better than any verbal description. The greater part is still before me in manuscript. It is my intention in the following contributions to endeavour to connect them together, adding to those already published many facts I find in MSS. The original drawings, made by my brother and by Messrs. Edward Forbes and Henry Goodsir (who were at that time my students and assistants), are still in my possession.
Determination of Species.—The determination of species as regards the Cetacea is one of much difficulty; Cuvier met this difficulty by an appeal to anatomy. The number of vertebræ composing the vertebral column (exclusive of the cephalic) seemed to me a tolerably secure guide in the determination of species,—being aware, however, that some doubted the method, believing that the number of the vertebræ might vary, first, with the individual, secondly with the age of the specimen. I still continue to be of my original opinion, that the number of vertebræ comprising the vertebral column, properly so called, may safely be trusted in determining the species of the Cetacea; and with this view I drew up the following Table, excepting from it the genus Dugong, which I have never considered to be a Cetacean:—
Tabular View of the Number of the Vertebræ in certain Cetacea.
(Cephalic vertebræ excluded.)
| Authorities. | |||||
|---|---|---|---|---|---|
| Species. | Cuvier. | Rudolphi. | Knox. | J. Hunter. | Hunter (Glasgow.) |
| 1. Mysticetus. | |||||
| Skeleton of the fœtus (the cervical reckoned as 7) of the Mysticetus borealis, Greenland | 48 | ||||
| Adult Mysticetus, Whale of Commerce. | unknown | ||||
| B. Mysticetus australis, True Whale of the Cape Seas | 59 | ||||
| 2. Balænoptera. | |||||
| Gigantic Northern Rorqual | 65 | ||||
| Specimen of Rorqual described by Rudolphi | 54 | ||||
| B. rostrata of Fabricius; on the authority of Van Beneden: A. Rorqual | 48 | ||||
| Great Whale at Antwerp. Van Beneden. Species not stated | 61 or 62. | ||||
| The lesser Rorqual of the North | 48 | 46 | 46 | ||
| Great Rorqual of the Cape | 52 | ||||
| 3. Physeter. | |||||
| Sperm Whale or Cachalot | 60 | ||||
| 4. Delphinus. | |||||
| D. Delphis | 67 | ||||
| D. Delphis. In my museum | 81 | ||||
| D. Delphis. In the Museum of Dr. R. Hunter, Glasgow | 90 | ||||
| D. Delphis. Dissected by John Hunter | 60 | ||||
| D. Phocæna | 66 | 65 | 51 | ||
| D. Ebsenii. Van Beneden | 90 | ||||
In a late number of the 'Bulletins of the Royal Academy of Brussels' I find some valuable remarks in respect of these points by M. Van Beneden. He praises, and deservedly, no doubt, the exertions of M. Eschricht to collect a proper Museum of the Cetacea. It appears, according to M. Eschricht, that at no age whatever do we find in true whales (meaning, I presume, the Mysticetus borealis and australis) any distinct vertebræ in the cervical region as in other mammals. A fusion of all into one bone or cartilage seems to take place even in the youngest fœtus. In the fœtus examined by me of this species (a specimen removed from the uterus of a true Mysticetus killed in the Greenland seas), I do not recollect the precise appearance of the cervical vertebræ; but the skeleton is in existence, and shall be referred to. To the skeleton of the Rorqual now in the Museum at Antwerp, and which seems to me of the same species as the one I dissected in Scotland (and of which the skeleton, prepared with infinite care by my brother and myself, was presented by me to the Town Council of Edinburgh, and is now preserved in the Zoological Gardens of the same city), he gives the following vertebræ:—
| Skeleton of the Rorqual at Antwerp— | Cervical | 7 |
| Dorsal | 14-15 | |
| Lumbar | 15 | |
| Caudal | 25[C] | |
| Total | 61 or 62 |
In the skeleton of the Great Rorqual now in the Zoological Gardens at Edinburgh, and originally dissected and prepared by my brother and myself, these vertebræ are—
| Cervical | 7 |
| Dorsal | 15 |
| Lumbar and Caudal | 43 |
| Total | 65 |
In that of the Lesser Rorqual I dissected in 1830, the skeleton of which I think is still preserved in the Museum of the University of Edinburgh, we found—
| Vertebræ. | |
| Cervical | 7 |
| Dorsal | 11 |
| Lumbar | 13 |
| Caudal | 17 |
| Total | 48 |
The specimen was that of a young animal, and of the same species, I believe, as the one described by Mr. Hunter and Fabricius; it is a distinct species, and not merely the young of the Great Rorqual.
I shall return to the Dugong, as not being a Cetacean, in a future Section: its skeleton has been examined in a masterly way by De Blainville, an anatomist and observer of the highest order, since the time I wrote and published my Memoir on the Dugong.
The first great step in the anatomy of the Cetacea is unquestionably due to Cuvier; but his dissections were almost confined to the genus Delphinus, or the common Porpoise of our coasts. I repeated all his dissections, and found them, as they almost always were, scrupulously exact; but when I came to examine Cetacea with whalebone instead of teeth, I was surprised to find how different, in fact, the anatomy of the two great families was. Scarcely in any great natural family do we find Cuvier's favourite theory of anatomical and physiological co-relations so entirely at fault as in the Cetacea. The teeth or whalebone, as natural-history characters, lead to no results; the whole structure of the interior defies all à-priori reasoning. The brain in whalebone-whales does not fill the interior of the cranium; so that the capacity of the one is no measure of the solid bulk of the other. Their food is various, having no relation to the teeth or buccal appendages; vascular structures surround the spinal marrow, and extend in the Balænopteræ into the cavity of the cranium, which seem to be without any analogy in other mammals, or, at the least, a very obscure one, and whose functions are wholly unknown.
Cetacea might with some propriety be divided into whales with whalebone, and whales with teeth. Those with whalebone have rudimentary teeth in both jaws in the fœtal state. Fossil Cetacea exist, and they seem to have been of both kinds, but, no doubt, were generically and specifically distinct from the recent. Judging from the remains of those I have seen, I am inclined to think that those with teeth were of a stronger and firmer build in the skeleton than those called recent; that the neck was longer, and the caudal portion of the column shorter than in the recent kinds, and that they approached the Saurians in form. There is a remarkable want of symmetry in the crania of some of the Cetacea; but most remarkable is the cranium of the Narwhal. Of this fact I have already spoken, in the article published in the Transactions of the Royal Society of Edinburgh.
Delphinus Phocæna. Dissection of a small Cetacean sent to me from Orkney in the month of May 1835.—This species is said to abound on the coasts, and to furnish a kind of fishery to the inhabitants. On dissection we found 81 vertebræ, exclusive of the cephalic. The species must be quite distinct from those previously and subsequently examined by myself and many others, in which the number of vertebræ ranged from 61 to 66. It is also, I think, distinct from the specimen I saw in Dr. R. Hunter's Museum in Glasgow, in which the number of vertebræ was 90, exclusive of the cephalic in all the cases. Thus it stands with regard to the Cetacea called Porpoises and Dolphins.
In certain species of Delphinus the vertical column is composed of 61 vertebræ, in others of 65, in others of 66, in others of 81, in others of 90.
The specimen I now describe was, no doubt, that of a young animal; and the skeleton was prepared, consequently, as a natural one. This method has the advantage of security against the loss of any important osseous structures, which too frequently happens when the bones require to be macerated. The bones contained little oil, and weighed, head included, only 7¼ lbs.; the whole animal, when entire, weighed 14 stone, or 196 lbs.; the skeleton therefore was about a twenty-fourth part of the whole weight. It was a female. The external nostrils terminated in a single orifice of a semilunar shape, with the concavity turned towards the snout. Measurements of young animals have not the importance of those of the adult; but I give them here because I think that the specimen, although young, had nearly attained its full growth:—
| ft. | in. | |
| Total length over the dorsum | 6 | 5-2/8 |
| Total length lateral surface | 6 | 11-2/8 |
| Total length abdominal surface | 6 | 11-2/8 |
| From the snout to the nostrils | 0 | 11-4/8 |
| From the nostrils to the dorsal fin | 1 | 6-4/8 |
| Base of the dorsal fin | 0 | 11 |
| From dorsal fin to foot of tail | 3 | 0-2/8 |
| Breadth of pectoral limb | 0 | 4-4/8 |
| From the snout to the organs of generation | 3 | 9-4/8 |
| Circumference anterior to the arm | 2 | 9 |
| Circumference anterior to dorsal fin | 3 | 2-4/8 |
| Circumference posterior to dorsal fin | 2 | 10 |
| Circumference at setting on of the tail | 0 | 8-4/8 |
| Length of pectoral limb | 0 | 10 |
| Breadth of tail | 1 | 2 |
| Greatest height of the dorsal fin | 0 | 9 |
From the notes taken at the time, I find that my brother remarks that the Dolphin of Orkney differed a good deal in shape from those found in the Forth and seas in the South of Scotland. There were, moreover, 16 more vertebræ than in the skeleton of the Common Porpoise of authors. The teeth generally weighed 2½ grains each.
Further, the muscles of the tongue, intrinsic as well as extrinsic, were extremely well developed. The isthmus faucium was 3 inches long. All this part was extremely glandular. A well-marked muscular gullet followed, composed of two layers of muscular fibres,—one circular internally, and one longitudinal externally. These latter sent a slip to the base of the arytænoid cartilages. The mucous membrane of the gullet had no true epidermic covering, and in this respect differed remarkably from the first gastric compartment, from which a cuticular lining could be peeled off, as strong as that from the sole of the foot in man. The larynx presented that organization so well described by the illustrious Cuvier, and which I believe to be peculiar to the whales with teeth. It differs very much, as I explained long ago, in its arrangement from that of Whalebone Whales,—a fact of which I think Cuvier was not aware. The cricoid cartilage was imperfect in form; the hyo-epiglottic muscles very strong. The proper arytænoid were present, and strong, but did not extend so high as in man; the thyro-arytænoid muscles were very fully developed. In the interior of the larynx there were no projections nor ventricles, no cuneiform cartilages, nor cornicula laryngis. The rings of the trachea formed complete circles.
Stomach.—The cuticular lining is limited to the first cavity or compartment. It is in the second compartment that is found the curious glandular arrangement first, I believe, described by me in the 'Transactions of the Royal Society of Edinburgh.' This structure is most probably not limited to the second compartment. There are four distinct compartments in the stomach of this animal. A dilated duodenum follows, 6 inches in length. It is possible that this may have been in some instances mistaken for a stomach. The valvulæ conniventes commence with the jejunum; these are longitudinal, and extend to within about 6 inches of the anus, terminating at a point where the intestine seems enlarged. The length of the intestines, large and small, was 90 feet; circumference generally about 2 inches. Thousands and tens of thousands of parasitical worms were found in the stomach, but none in the intestine. In the stomach also we found four mandibles of the cuttlefish, but no remains of anything in the intestines, and no parasites.
Heart and Vessels.—The heart weighed exactly one pound. The Eustachian valve was small, that of Thebesius imperfect. The aorta proceeded for about 3 inches of its course before giving off any branches. At a point corresponding to the 15th or 16th lumbar vertebra the vessel divided into the common iliacs. The art. sacri media, its continuation, continued its course protected by the V-bones, and giving off branches corresponding to the intervertebral spaces.
Brain and Nervous System.—The erectile tissue surrounding the spinal cord and origin of the spinal nerves in the Cetacea did not extend into the interior of the cranium. The entire encephalic mass weighed 2½ lbs.: cerebrum, 2 lbs.; cerebellum, ¼; pons and medulla, ¼ = 2½. Compared with a drawing of Camper of the Delphinus Phocæna, the brain was found to differ remarkably, in being much broader in the line of the middle and posterior lobes. In no animal did I ever find the fibrous structure of the brain so well marked; and this extended to the cerebellum[D]. I give here some measurements of the brain, which may be of use to future observers. The brain is short from before backwards, but broad transversely:—
| Antero-posterior diameter | 5-2/8 | inches. |
| Breadth | 8 | inches. |
| Greatest breadth of the cerebellum | 4 | inches. |
| Length of the cerebellar hemisphere | 4-6/8 | inches. |
| Depth of ditto | 3-2/8 | inches. |
| Weight of the encephalic mass | 2½ | lbs. |
| Depth of the interhemispherical fissure | 1-2/8 | inches. |
| Length of the corpus callosum | 1-7/8 | inches. |
| Weight of cerebrum | 2} | |
| Weight of cerebellum | 0¼} | = 2½ lbs. |
| Weight of the pons and med. oblongata | 0¼} |
Nerves.—The 7th pair was found to be unexpectedly large and firm, including both portions. The anterior roots of the spinal nerves were far more numerous than the posterior or dorsal.
Muscles.—The panniculus carnosus, strong and fleshy, extended nearly over the whole trunk. The recti abdominis were powerful, and attached inferiorly in this way:—A portion runs to the pelvic bones; a much stronger to a strong aponeurosis, situated between the anus and the root of the tail.
The erector muscles of the spine (sacrolumbalis, longissimus dorsi and multifidus spinæ) weighed fully 16 lbs. They had but slender costal attachments; but their spinal (small delicate tendons) were innumerable. The scaleni were very large; and the vessels held the same relation to them as in man. The serratus magnus was comparatively small. The larger rhomboid had no spinal attachment; the minor rhomboid seemed to be the larger of the two. The pectorals were comparatively small. The adipose tissue appeared to be wholly confined to the subcutaneous region. The muscles were of a deep brown colour, full of blood, with a short, dark, and well-flavoured fibre: when cooked, they had a strong resemblance in flavour and taste to the flesh of the hare.
Part II. The Balæna Whales, or Whales with Whalebone.
In February 1834 a young whale of the family of Balæna Whales was caught near the Queensferry, in the Firth of Forth. One much larger had been seen some time before, but escaped. I purchased it for dissection, although I was aware that it was impossible for me, during the hurry of the winter session, to devote much time to it. But I had able assistants (Mr. Henry Goodsir, Mr. Edward Forbes, and my brother), from whom I expected a good deal of aid. Some very beautiful drawings of this whale, made for me by Mr. Edward Forbes and by my brother, are still in my possession.
It was easy to see, by the dorsal fin and by the numerous plaits or folds on the abdominal surface of the throat and chest, before any dissection, that the specimen was a young Balænopterous whale, differing in a great many points from the true whale or Mysticetus: for, 1st, the form of the head was entirely different; 2nd, it had a dorsal fin; and, 3rd, occupying the lower surface of the throat and thorax were numerous folds of the integuments. To this class of whales I have been in the habit of giving the name of Rorqual, to distinguish them from the other class of Whalebone Whales, the Mysticetus both borealis and australis.
It appears from my notes, that at that time M. G. Cuvier considered the species I now describe as identical with the Great Rorqual I had described about two years previously; but I felt convinced then, as now, that they form distinct species, and in this opinion some continental anatomists seem to coincide.
Being persuaded that there was some inaccuracy in former drawings of the species, I had the specimen suspended and drawn with great care by Mr. Edward Forbes. This position explained the mechanism of the mouth, showing its great size, even in the short Balæna Whales; its great capacity in the Mysticetus had never been doubted.
As to the species, the conclusion I arrived at was, that the specimen belonged to that termed by Fabricius rostrata, and that individuals of the species had been seen by John Hunter, Sir James Watson, and Fabricius.
| Measurements. | ft. | in. | |
| Total length of the specimen | 9 | 11 | |
| Circumference immediately behind the pectoral extremities | 5 | 2 | |
| Circumference where the folds or rugæ terminated | 4 | 8¼ | |
| Ditto of the tail at its origin | 1 | 5½ | |
| Length from the back fin to the setting on of the tail | 2 | 10 | |
| Length from the snout to the ear | 3 | 0 | |
| Length from snout to nostrils | 1 | 4 | |
| Length of lower jaw | 2 | 3 | |
| Length of arm; inner side | 1 | 3 | |
| Length from the angle of the mouth to the arm | 1 | 3 | |
| Length from snout to arm | 2 | 9 | |
| Length of tail in depth | 0 | 11 | |
| Length of back fin at the base | 0 | 8 | |
| Height of back fin | 0 | 8½ | |
| From top to tip of tail | 2 | 8½ | |
| Stomach:—1st compartment, in length | 1 | 2 | |
| 2nd compartment, in length | 1 | 4 | |
| 3rd compartment, in length | 0 | 8 | |
| 4th compartment, in length | 0 | 7 | |
| 5th compartment, in length | 0 | 3 | |
| Spleen weighed 4 ounces; its length was | 0 | 5 | |
| Liver, 9 lbs. | |||
| Small intestines, length | 20 | 0 | |
| Large intestines, length | 2 | 4 | |
| Kidney, weight 2¼ lbs. | |||
| Brain (including 2 inches of spinal marrow), 3½ lbs. | |||
| Cerebellum, pons, and 2 inches of spinal marrow, ¾ lb. | |||
| Great hemisphere of the brain measured 3 inches in length, in breadth, 6½; at the base, 8 inches. | |||
| Tuber annulare | 0 | 1-2/8 | |
| Olfactory nerves, in length | 0 | 1½ | |
| Ditto, breadth | 0 | 2½ | |
| Skeleton:—Length of cranium | 2 | 11 | |
| Greatest breadth between the orbits | 1 | 3 | |
| Length of vertebral column | 7 | 8 | |
When we compare the skeleton of this Rorqual with the Gigantic Rorqual I also dissected, we find as follows:—
| R. giganteus. | R. minor. | |||
| Cervical | vertebræ | 7 | vertebræ | 7 |
| Dorsal | 15 | 11 | ||
| Lumbar, sacral, caudal | 43 | 30 | ||
| —— | —— | |||
| 65 | 48 | |||
These differences must be specific.
At the extremity of the snout in either jaw there were 8 strong bristles, being the only vestiges of hair found on the external surface. The mouth was of great size; the tongue large and tolerably free, and of a pale rose or vermilion colour. The baleen, where deepest, measured about 4 inches; there were 370 plates on each side; but anteriorly and posteriorly these plates were reduced to mere bristles.
The isthmus faucium allowed the closed hand to pass through it; through this isthmus I do not believe that any water ever passes into the pharynx, unless it be accidentally, as in man. The "spout" of the Whalebone Whale is composed, no doubt, of the pulmonary vapour, and not of any water received into the pharynx from the mouth.
The stomach seemed composed of five compartments externally, but presented only four when laid open, the fifth being manifestly the duodenum. In the intestines no remains of food were found, but abundance of intestinal worms, and a substance strongly resembling the human meconium. There was an ilio-cæcal valve as distinct as in man. In the rectum the folds of the mucous membrane were transverse.
Organs of Respiration.—The external nostrils were double; and the cavities of the nostrils provided with the remarkable cartilages and muscular apparatus I discovered and described in the anatomy of the Great Rorqual. In this specimen they were about 4 inches in length, but of as many feet in the large Rorqual. The mode of breathing in the Rorquals does not differ much from that in man, with the exception of the apparatus of the protruding cartilages, which in man are rudimentary.
The Olfactory Nerves were quite as large as in other mammals; and in this respect the Balæna Whales are quite unlike the Dolphins[E].
The trachea communicated, near its upper part, with a sac or pouch; the lungs were each composed of a single lobe. The rings of the trachea were mostly deficient anteriorly. In the heart the fœtal arrangements had wholly disappeared. The dura mater seemed divisible into three layers, the external being vascular. A remarkable vascular substance connected with this layer covers the back part of the brain and cerebellum, extending into the spinal canal, and even into the chest. At the base of the brain the vascular plexus was about 2 inches in thickness. It is, as is well known, a sort of erectile tissue, of whose functions we are wholly ignorant. It is not confined to this course, but extends to the neck, and, passing through the foramina intervertebralia, fills the intercostal spaces exterior to the pleura.
There was evidently a canal in the centre of the spinal marrow. Wherever the nerves of the lungs and stomach were traced, they terminated in loops. We did not observe in the Great Rorqual any tracheal pouch like that in the smaller; but it may have escaped notice: if absent in the Great Rorqual, it would be another proof of the distinctness of the species.
The doubts raised by M. St. Hilaire, as to the Whale being a mammal in the true sense of the term, were set aside long ago by an appeal to facts. The young of the Whale tribe suckle like the young of all mammals; nevertheless I showed, in 1834, that the lactiferous glands in the Balænopteræ differ in structure from the same organs in most mammals.
I do not find in my notes anything to add to the description of the Great Rorqual already published in the 'Transactions of the Royal Society of Edinburgh' for 1827, to which I beg leave to refer the reader.
A single remark must be added regarding the nature of the vascular plexus which, in the Cetacea, surrounds the spinal marrow, and extends into the chest. On selecting the artery which seemed to form the plexus, which was, if I rightly recollect, in this instance an intercostal artery, and dissecting it under water, I found, to my surprise, that the artery, so long as I followed it, never gave off any branches, but continued of the same calibre throughout, making innumerable flexuosities or turnings. Thus, on a plexiform mass of this kind being cut across, the first impression is, that a great number of arterial branches or arteries have been divided, whilst in fact the entire plexus seems to be formed of one artery.
As was to be expected of animals so much withdrawn from human observation, there is but little to say on the natural history of the Cetacea properly so called. Their food, no doubt, is various, and seems to have little or no relation to the character of their dentition. The enormous Cachalot, with its vast teeth implanted only in one jaw, is generally understood to prey chiefly on the Cuttlefish. The food of the true Whale, or Mysticetus, is well known to be the Clio and other smaller Mollusca, with which certain regions of the ocean abound; the same, or similar, is probably the food of the more active and restless Rorquals, found in both hemispheres. The Dolphins, or Toothed Whales, generally prey, no doubt, on fishes of various kinds; yet, even as regards these, it has been proved by my esteemed friend, the late Mr. Henry Goodsir, that some of the largest, following in the wake of the herring shoals, prey not on these, but on the various microscopic food (the Entomostraca and other marine animals) which I was the first to prove to be the natural food of many excellent gregarious freshwater fish, as the Vendace, Early Loch Leven Trout, the Brown Trout of the Highland and Scottish lakes generally, and of the Herring itself[F]. It is scarcely necessary to add, that the complex apparatus connected with the exterior nostrils of the Dolphins is wholly wanting in the Balæna Whales,—a fact of which M. Cuvier was not aware when he wrote his celebrated Treatise on Comparative Anatomy.
Appendix.—Since writing the above, I have received an answer to a letter I addressed to my friend, John Goodsir, Esq., Professor of Anatomy in the University of Edinburgh. The request contained in my letter to Mr. Goodsir was, to examine for me the skeleton of a fœtal Mysticetus now in the University Museum. The fœtus from which this skeleton was prepared was removed from the uterus of the mother, killed in the North Seas by the seamen of a whaling ship, by one of my former students, Mr. R. Auld, who presented the specimen to me. The point at issue was the composition of the cervical vertebræ in the true or Greenland Whale, the Balæna Mysticetus. M. Van Beneden, to whose memoir I have referred in the commencement of this, says, on the authority of Eschricht, that at no age whatever do we find in true Whales (meaning, I presume, the Mysticetus borealis and australis) any distinct vertebræ in the cervical region, as in other mammals. A fusion of all into one bone or cartilage seems to take place even in the youngest fœtus. Now, I had enjoyed the rare opportunity of dissecting the fœtus of the Mysticetus, and I knew that the skeleton, prepared with the greatest care, was still preserved in the Museum of the University of Edinburgh. I wrote to Mr. Goodsir to re-examine this point for me, for I did not find in my notes any confirmation of the observations of Eschricht. Mr. Goodsir's reply to my note is as follows:—
"University, Edinburgh,
Sept. 30, 1857.
"My dear Sir,
"In the skeleton of the fœtal Mysticetus now in the University Museum, the bodies of the axis and atlas have shrivelled up together, having evidently consisted of cartilage only; but the bodies of the five posterior cervical vertebræ are beautifully distinct, having well-formed osseous centres, which give them more of the configuration of the succeeding vertebral bodies than they present in their compressed form in the adult.
"The neural arches in the cervical region of this skeleton are five in number; the two anterior, which are distinctly those of the atlas and axis, have an osseous nodule on each side, where the transverse processes pass off. The third arch belongs to the third vertebra, the fourth and fifth to the sixth and seventh. These three arches are cartilaginous, and present no osseous centres. It is impossible to determine from the preparation whether the arches of the fourth and fifth vertebræ had been cut away in dissecting the parts, or whether they have shrivelled up in drying; but as the skeleton was very carefully prepared, and as these two arches are deficient (at least laterally) in the adult Mysticetus, I presume that the cartilaginous matrices were at least extremely delicate in the fœtus.
"I believe I have stated all the facts, afforded by this skeleton, which bear upon your questions. They appear to me to afford no support to the views to which they refer.
"Yours very sincerely,
(Signed) "John Goodsir."
The conclusion I arrived at is this,—that the actual number of cervical vertebræ in the Mysticetus is, as in most other mammals, seven, and that, notwithstanding their earlier fusion, they are originally quite distinct.