PSEUDORCA CRASSIDENS. 199 



grisens are not so broad as those of the ca'ing-whales, (nay not even so broad as those of our 

 crassidens) ; but judging by the figures,^ this dolphin seems, nevertheless, as far as the rest of 

 the beak is concerned, to be much more similar to these Cetaceans, than to the type of any other 

 species. Bvit the case is somewhat different in the species which we are here describing, the 

 surface of the beak is from its origin somewhat convex, the dental row occupies almost the whole 

 length of the beak, the superior maxUlaries have still a considerable thickness, in order to 

 leave room for the very deep sockets of the teeth, and are, generally speaking, much more hke 

 the same bones of an Orcathan those of the ca'ing- whale or the Grampus. 



The asymmetry pervading the whole cranium also affects the intermaxillaries, and 

 especially the hindmost part of these bones. The right one is perceptibly broader than 

 the left, and is quite contiguous with the corresponding nasal bone, its posterior extremity 

 inserting itself between the latter and the superior maxillary ; the left, on the contrary, does not 

 extend quite so far backwards, and more especially does not quite reach the nasal bone, which is 

 also influenced by the general asymmetiy, being considerably smaller than the right one. Just 

 before the nostrils there is a notch in the inner edge of both of the intermaxillaries, and in the 

 space thus left a portion of the superior maxillaries become visible. In conformity with the 

 general obhquity of the head the visible part of the right superior maxillary is always 

 somewhat larger than that of the left; but the portion of these bones, laid bare in this 

 manner, may, in different individuals, be sometimes a little larger, sometimes a little smaller. 

 Something very similar also takes place in the common ca'ing-whale, and (though in a smaller 

 degree) in the northern killers, and various other dolphins, amongst others in the common 

 porpoise. On the contrary, it does not seem to be the case with Grampus griseus, to judge by 

 Cuvier's figures, and from this Cetacean the dolphin here described also differs in another and 

 more important respect, as far as this part of the skull is concerned. The intermaxillaries of 

 Grampus griseus are dilated in front of the nostrils, according to the statements of both Cuvier" and 

 J. E. Gray,'' so as to cause a convexity in this place ; but no trace of anything of the kind is to 

 be found in our species, in which the intermaxillaries are, on the contrary, somewhat depressed at 

 some distance before the nostrils, and the distinctly defined three-cornered region in this place, 

 denominated by Gray the " triangle," here forms a slight depression, as in most other 

 dolphins. 



As far as may be inferred from Owen's short description and small figures of his Phocæna 

 crassidens, it must be quite similar to our dolphin, as to all the details of the characters 

 of the cranium which have been examined above ; it has, therefore, hitherto been unnecessary 

 to refer particularly to the fossil form, and compare it with our specimens. We shall 

 now mention the only point, as to which the resemblance may at first glance seem doubtful, 

 and which accordingly must be considered more minutely. We know that in the dolphins the 

 vomer is sometimes visible on the inferior surface of the beak (sometimes even in two different 

 places), and thus it may have some share in forming the palatine surface ; sometimes on the 

 contrary, it does not appear there at all. Now Owen states that the vomer appears on the 



^ ' Reclierches s. 1. Oss. Foss.,' 4me ed. Atlas, tome deuxieme, pi. 223, figs. 1 and 2. 

 " Ibid., 4me ed. tome 8, 2me partie, p. 125. 



■' ' The Zoology of the Voyage of H.M.S. Erebus aud Terror,' " Mammalia," p. 30. Catalogue of 

 the Mamm. iu the CoU. of the Brit. Mus., P. ], Cetacea, p. 82. 



