224 PEOFESSOB FLOWEE ON THE EECENT ZIPHIOID WHALES. 



lumbar 12, caudal 19 ; total 48. This appears to be very nearly the usual number in 

 Ziphius and Mesoplodon, and to exceed that of Hyperoodon by 3. 



Though generally resembling that of the three allied genera, the column differs from 

 Mesoplodon sowerbyi (Van Beneden and Gervais, pi. 22) chiefly in the spines of the 

 anterior dorsal region being smaller, more pointed, and more recumbent — also in all 

 the other spines sloping more backwards, and being smaller in proportion to the body, 

 both in height and width from before backwards ; thus in a middle lumbar vertebra, 

 the antero-posterior diameter of the spine in Sowerby's Dolphin is about two thirds 

 the length of the body, while in Berardius it is little more than one third. M. densi- 

 rostris and another as yet undetermined species in the Sydney Museum agree generally 

 with M. soiverbyi in these respects, judging from photographs of their skeletons sent by 

 Mr. Krefft. Ziphius australis appears in Burmeister's figure to be rather intermediate 

 between Mesoplodon and Berardius in the form of the spines of the vertebrae. In 

 Hyperoodon the spines are as long as in Mesoplodon and as slender as in Berardius. 



Cervical Vertebras. — The vertebrae of the neck (PL XXVIII.), especially those of the 

 posterior part of the region, are better developed than in most Dolphins, and, indeed 

 (except for the coalescence of the first three), bear a considerable resemblance to those 

 of the Beluga. Among the Ziphiinse, as far as is yet known, Mesoplodon and Ziphius 

 both approach Berardius in the structure of this important region, while, as will be 

 seen, Hyperoodon offers the greatest possible contrast. 



The entire length of the bodies of the seven cervical vertebra?, when placed in con- 

 tact, is 10 inches. The atlas, axis, and the third vertebra are united firmly by their 

 bodies ; and the first two are also united by the lamina? of the neural arches, but the 

 axis and the third only by that portion of the arch corresponding to the zygopophyses, 

 the upper part being free. All the remaining vertebra? are separate throughout. The 

 free ends of their bodies show traces of the epiphyses by which they have been com- 

 pleted ; and their surfaces appear so completely formed or finished, as it were, that it 

 does not appear probable that much, if any, further union would have taken place had 

 the animal attained a greater age. 



In Hyperoodon not only is the whole length of the cervical region scarcely more than 

 half that of Berardius, but the bodies of all seven vertebra? are firmly united together, 

 and the spines of all, except the seventh, join to form a single elevated conical mass; 

 the vertebra?, except the first two and the last, are evidently extremely compressed, 

 almost rudimentary in fact. In Ziphius australis, according to Burmeistcr, the first, 

 second, and third are united, and also the fourth and fifth to each other, though not to 

 the third, and the sixth and seventh are free. In the specimen of Ziphius cavirostris, 

 from Corsica, briefly described in Fischer's memoir, the six anterior vertebra? are stated 

 to be united and the seventh free. In Sowerby's Mesoplodon at Brussels the first two 

 only are united, and all the others free. In M. densirostris, according to Krefft 1 , "the 

 1 P. Z. S. 1870, p. 426. 



