| Measurements. | A | B |
|---|---|---|
| Total length | 715 | a633 |
| Length of rostrum | 413 | a325 |
| Distance from occipital condyles to distal end of maxillæ | 612 | 567 |
| Breadth between centers of orbits | 309 | 279 |
| Breadth between zygomatic processes | 310 | 278 |
| Breadth between temporal fossæ | 228 | 212 |
| Breadth between postorbital processes of frontals | 323 | ... |
| Breadth of rostrum at base (between maxillary notches) | 172 | b158 |
| Breadth of rostrum at middle | 40 | 44 |
| Depth of rostrum at middle | 52 | 42+ |
| Greatest breadth of anterior nares | 56 | 54 |
| Greatest breadth of premaxillæ proximally | 130 | 118 |
| Greatest breadth of premaxillæ in front of nares | 108 | 109 |
| Length of temporal fossa | 92 | 86 |
| Depth of temporal fossa | 63 | 46 |
| Antero-posterior length of orbit | 96 | 82 |
| Breadth of foramen magnum | 38 | 39 |
| Length of tympanic bulla | 48 | ... |
| Breadth of tympanic bulla | 32 | ... |
| Length of mandible | 610 | ... |
| Length of symphysis | 138 | ... |
| Distance from anterior end of mandible to alveolus | 166 | ... |
a Tip of rostrum lacking. b The skull is much worn around the left notch and the measurement is only approximate.
EXTERNAL FORM.
The photograph of the head ([Pl. 40], fig. 4) shows that the end of the beak was quite blunt, and the lower jaw quite a little longer than the upper. The superior margin of the lower jaw, which is concave in front of the tooth, is strongly convex and elevated at the side of it and behind it. The inferior margin of the upper jaw is straight anteriorly, but farther back appears to be pressed upward by the tooth. An examination of the skull shows that the mandible can be lowered so that the teeth are below the upper jaw, but when so lowered the space between the teeth and the upper jaw on each side is barely a quarter of an inch (6 mm.). With the integuments in place, it is doubtful whether the mouth could be opened any wider than is shown in the photograph. The convexity of the head, shape of the blowhole, position of the eye, etc., do not appear to differ materially from the same characters in adults of M. bidens.
Genus ZIPHIUS Cuvier.
ZIPHIUS CAVIROSTRIS Cuvier.
Ziphius cavirostris Cuvier, Oss. foss., 2d ed., vol. 5, 1823, p. 353. Hyperoödon gervaisii Duvernoy, Ann. Sci. Nat., ser. 3, Zoöl., vol. 5, 1851, p. 49. Ziphius gervaisii Fischer, Nouv. Arch. Mus. Paris, vol. 3, 1867, p. 55. Hyperoödon semi-junctus Cope, Proc. Acad. Nat. Sci. Phila., 1865, p. 15. Ziphius semijunctus True, Proc. U. S. Nat. Mus., vol. 8, 1886, p. 586. Ziphius grebnitzkii Stejneger, Proc. U. S. Nat. Mus., vol. 6, 1883, p. 77.
It has not seemed to me necessary in the present connection to attempt to cite all the multitudinous names which have been given to this species, especially as those zoologists most competent to judge, including Van Beneden, Flower, and Turner, after detailed consideration, have concluded that but one species of Ziphius, or at most two species, exist at present.[35]
Nearly all the skulls in European museums are assigned by the zoologists mentioned to Z. cavirostris proper, but some doubt has been entertained regarding two or three European skulls, and one specimen from Argentina, described by Burmeister. These last-mentioned specimens have been thought to possibly represent a second species, Z. gervaisii. The principal characters of the latter are the narrow, flat premaxillæ, the lack of a prominent mesirostral ossification, and small teeth. From the large series of skulls in the National Museum, I am able to dispose of the doubt concerning Z. gervaisii. I find that wherever the characters above mentioned occur the sex (when known) is female. There is every reason, therefore, to believe that Z. gervaisii is the female of Z. cavirostris.[36] I will return to this point again later.
In 1865 Cope described a species from Charleston, South Carolina, under the name of Hyperoödon semijunctus. In 1886 I referred it to the genus Ziphius, but was in doubt as to its specific identity. I thought that it might represent Z. gervaisii, which is interesting in the present connection because the type-specimen was a female.