SECTION I (Mammalia).
In dealing with this class of hosts, exclusive of man, I shall notice the entozoa of the various orders successively, taking the arrangement which I employed many years since when writing the Mammalian Division of a popular treatise called the ‘Museum of Natural History.’ The internal parasites of those orders which happen to embrace important domesticated animals will necessarily receive more attention than the others; some notice of the ectozoa being likewise added.
Part I.—Quadrumana (Monkeys).
Fig. 54.—Cœnurus lemuris. 1, Colony; 2, portion of the ectocyst (enlarged); 3, scolex-head (magnified 40 diameters); 4, hooks (magnified 260 diameters). Original.
Monkeys are less afflicted with flukes than most animals. The species known to me are Distoma laciniatum, found by Brongniart in the pancreas of Simia maimon; D. orbiculare and Amphistoma emarginatum, from the intestines of Cebus trivirgatus; and Bilharzia hæmatobia, a single specimen of which I obtained from Cercopithecus fuliginosus. The monkeys of the Old World rarely harbor full-grown tapeworms, but Cysticerci are abundant (Cyst. tenuicollis, C. cellulosa, C. pileatus, C. crispus). The common hydatid (Echinococcus polymorphus) has been found in many of the Simiæ, and by myself in a Madagascar lemur (L. macaco). Dr Leidy also obtained three hydatid cysts from a large monkey. On the last day of the year 1857 I obtained some polycephalous hydatids (Cœnurus lemuris) from a ring-tailed lemur. They infested the liver, being more abundant in the lungs. They occupied both sides of the chest. Loose and detached specimens also existed in the cavity of the right pleura. Most of those occupying the chest were connected to the pleura, forming vesicular, semi-transparent masses, varying in size from a filbert to a large walnut, many being united in bundles of much larger size. One of these masses is here drawn (1, fig. 54). It consists of four large Cœnuri, their combined pedicles forming a single stalk. A fifth hour-glass-shaped rudimentary Cœnurus is also visible. Every Cœnurus supports a variable number of lobules, each lobe supporting one or more papillæ. Here and there the papillæ resemble chains of beads. No trace of tapeworm heads could be seen, but under a half-inch objective glass, I found some flat papillæ presenting oval depressions at the surface (2, fig. 54). On examining some of the larger papillæ they were found to consist of membranous layers folded one within the other. These were carefully dissected and examined with the aid of needles, when each one showed in the centre a well-formed tapeworm head with four characteristic suckers, and a prominent rostellum supporting a double coronet of hooks, thirty-two of the latter in all (3, fig. 54). The hooks displayed a marked disparity of size and form. Each hook showed conspicuous anterior and posterior root-processes, the larger set of hooks individually measuring about 1/225″ and the smaller 1/330″ in length (4, fig. 54). There were numerous calcareous corpuscles. The interior of each vesicle was filled with a fluid, in which there were no free scolices. On referring to my notes I find that the lemur had arrived in England about four months previously.
Larval cestodes do not appear to be common in the monkeys of the New World (Cebidæ), nevertheless I found several Cysticerci in the liver of Macacus radiatus (Feb. 19th 1857), and a single specimen in the sooty monkey (Dec. 4th 1857). They were wrongly described by me as Cercariæ. The Cebidæ are largely infested with tapeworms (Tænia megastoma and T. rugosa). A species of Ligula (L. reptans) has likewise been found beneath the skin of Callithrix sciureus and in one of the marmosets (Hapale melanurus). Perhaps the most common helminth infesting monkeys is the nematode called Filaria gracilis. I have examined specimens from the orang, the capuchin, and the spider monkey. This parasite commonly occupies the abdomen, coiled beneath the peritoneum, or within folds of the mesentery. It sometimes occurs beneath the skin, or within the connective tissue of superficial muscles. The female worm has been known to reach a length of five feet. In 1873 Mr Samuel Smith, of Clifton, sent me five specimens of this worm. From one of the males, which measured twenty inches in length, I procured some spermatozoa, and found their long diameter to average 1/1400″. These corpuscles and other structures, as well as the worm itself, are figured in my ‘Notes on Entozoa’ quoted below. Next in frequency, perhaps, is the whipworm (Trichocephalus dispar), which monkeys of all kinds harbor in common with man. Besides these nematodes, Physaloptera dilatata is found in the stomach of American monkeys, and Ascaris distans also (in the large intestine of marmosets more particularly). This Ascaris has also been found in Cercopithecus fuliginosus and in Simia sabæa. A small spiroptera is said to infest the walls of the stomach of Simia maimon. To Dr Murie I am indebted for a large roundworm (Ascaris lumbricoides) taken from the intestine of a chimpanzee (Troglodytes niger), and also for a smaller nematode taken from a green mona-monkey (Cercopithecus). This I have described and named Ascaris cuspidata. From the intestines of a chacma (Cynocephalus porcarius) M. Schafhert procured sixteen examples of a small strongyle (Str. attenuatus, Leidy).
The singular monkey known as Tarsius spectrum is liable to be attacked by a filaria (F. lævis), which is found beneath the skin. At least two species of Echinorhynchus (E. spirula and E. elegans) are known to infest monkeys. I have carefully examined and figured E. elegans in the ‘Zoological Society’s Proceedings,’ from specimens supplied to me by Dr Murie. They had been obtained from a pinche monkey (Hapale œdipus) from New Granada. I am under the impression that Diesing’s original description of this parasite is the only one that exists. I have gone over his numerous memoirs contributed to the Vienna Academy, but can find nothing beyond the specific characters given in his ‘Systema.’ All the specimens in the Vienna Museum, whence his description is taken, were collected by Natterer. They were procured from the marakina (Midas rosalia), from two other true marmosets (Hapale ursula and H. chrysoleuca), and from a squirrel monkey or tee-tee (Callithrix sciureus). In the monkey which died at the Zoological Society’s Gardens the cause of death was not clearly due to the parasites; nevertheless, the mucous layer of the intestine, to which the entozoa were attached, showed deep conical pits or depressions at the spots where the worms had anchored themselves. During the perfect retraction of the proboscis of this Echinorhynchus the centre is represented by a wide opening which communicates with a cavity beneath. The end of the neck thus forms a sort of collar, or rosette, made up of rays arranged like the spokes of a wheel. When the proboscis is exserted this collar is more or less convex, but it becomes slightly concave when the proboscis is retracted. Diesing recognised twenty-four rays; they probably vary from that number up to twenty-eight, at least I counted twenty-seven in my specimens. During exsertion the proboscis forms a nipple-like projection. According to Diesing it supports three rows of hooks, but I certainly saw four rows. When separately magnified these hooks present very different appearances as to size and contour. These variations I believe to be due to growth. The largest hooks measured about 1/200″ in length.
As regards insect parasites, it is well known that monkeys are largely infested by fleas, but the species have not been much studied. The same may be said of their mites (Acaridæ). A species of Pentastoma (P. tornatum, Creplin) has been found occupying little cysts of the peritoneum and omentum in Simia maimon and S. cynomulgus. Under a synonym (Linguatula Diesingii) it has been very fully described by Van Beneden. Another species (P. subcylindricum) has been found attached to the lungs and liver of a marmoset (Hapale chrysopygus). Dr Leidy found five specimens of P. euryzonum in cysts on the subperitoneal surface of the liver of Cynocephalus porcarius. Leuckart believes that Dr George Harley’s P. polyzonum is the adult state of P. euryzonum, and that P. subcylindricum is the larva of P. proboscideum, found in Boa constrictor and other serpents.