It is demonstrated from the foregoing discussion, I think, that the sexes can be distinguished by the skulls, when adult, or by the teeth alone.
Reverting now to Ziphius gervaisii, which was mentioned on [p. 30] as perhaps constituting a separate species, it will be seen by examining the figures given by Gervais[44] of the skull on which it was based that the latter presents the combination of characters peculiar to the female of Z. cavirostris. This skull, which was from Aresquiers (Hérault), France, was 888 mm. long, and hence, presumably, adult. The mesirostral ossification is but slightly developed, the prenarial concavity moderate, the teeth small, slender, and cylindrical, with closed roots and a diameter of 14 mm. There seems to be no sufficient reason for regarding this skull as representing a species distinct from cavirostris.
The specimen from Buenos Ayres described and figured by Burmeister in 1868[45] was an immature male. In the skull the mesirostral ossification was lacking, the premaxillæ were flat, and the teeth conical and acuminate, with open roots, and a diameter of 12 mm. This individual was 12 feet 11½ inches (3.95 m.) long, and hence about as long as the Charleston specimen, but the skull was apparently 680 mm. long, while that of the Charleston specimen is 797 mm. long. In the latter the teeth are 45 mm. long and 10 mm. in diameter, while the tooth figured by Burmeister is 31 mm. long and 12 mm. in diameter. From these data it appears improbable that the sex of immature individuals can be determined from the skull or teeth.
TEETH.
The teeth of the various North Atlantic and North Pacific specimens merit a somewhat more detailed description than is given on pages [50] to [53]. Six pairs of teeth from six different individuals are available for comparison. Their dimensions are as follows:
Dimensions of the teeth of Ziphius cavirostris.
| Cat. No. | Locality. | Age. | Sex. | Teeth. | |
|---|---|---|---|---|---|
| Length. | Greatest diameter. | ||||
| mm. | mm. | ||||
| 21975 | Charleston, South Carolinaa | Young | Female | 45 | 10 |
| 20971 | Barnegat City, New Jersey | Adult | Female | 56 | 13 |
| 22069 | Bering Island | Adult | (Female?) | 41 | 14 |
| 20993 | dob | Adult | (Male?) | 48 | 25 |
| 21248 | do | Adult | (Male?) | 58 | 30 |
| 49599 | Newport, Rhode Island | Adult | Male | 63 | 29 |
a Type of Z. semijunctus. b Type of Z. grebnitzkii.
21975. Charleston, South Carolina.—Young female. (Type of Z. semijunctus.) The teeth are slender, conical, and acuminate, largest at the base and tipped for about 2 mm. with white enamel. The remainder of the teeth is coated with a thin layer of cement. The teeth in what appears to be their natural position protrude horizontally from the mandible for about 17 mm. They are slightly curved upward near the tip and are oval, or elliptical, in section, the transverse diameter being a little less than the vertical diameter. They are a little flattened externally. The surface is smooth. They are open at the root, and hollow. ([Pl. 38], figs. 1, 2; [pl. 22], fig. 1.)
Doctor Manigault, curator of the Charleston Museum, wrote to Professor Cope regarding these teeth, as follows: