I 



Prof. Eschricht on the Gangetic Dolphin. 281 



in some it comes close to the whitefisk and the allied great 

 tooth-whales, in others to the dolphin of the Amazon ; while 

 again in some respects it stands quite isolated. 



The most striking peculiarity in its cranium is manifestly the 

 two vaulted osseous crests on the upper jaw. These not only 

 resemble the crests of the Hyperoodon, but are essentially of the 

 same form; the only difference consisting in their being more 

 vaulted in the Gangetic dolphin, and having in consequence a 

 greater space between them; but they rise similarly from the side 

 of each upper jaw-bone, and approach more closely together along 

 the middle, by age. This has been pointed out by Mr. Gray, as re- 

 gards our dolphin ; and in my memoir last quoted (p. 98), T have 

 thrown out a hint, that something very similar takes place in the 

 Hyperoodon : "Mr. Gray's Hyperoodon latifrons is a good species, 

 founded on a cranium from the Orkney Islands with the crests 

 on the upper jaw unusually thick ; and yet it may perhaps be 

 only the cranium of an old male of the common Hyperoodon." 

 This supposition has since become a matter of certainty ; for all 

 crania of old Hyperoodons, at least of males, have the crests 

 similarly developed, as has actually been verified in a skeleton of 

 an old individual of this kind, sent to my worthy colleague Prof. 

 Steenstrup from the Feroe Islands, and by him kindly trans- 

 ferred to the zootomic-physiologic museum of our University, 

 under my charge. It is therefore fully proved, in my opinion, 

 that, while on the one hand this specific formation can no longer 

 be considered as characterizing singly the species hitherto founded 

 on it ; so, on the other, does it establish the similarity, in that 

 respect, between our dolphin and the Hyperoodon proper. It is, 

 further, very striking, that in consequence of that formation, 

 the Gangetic dolphin is more nearly allied to the Hyperoodon 

 than to the Micropteron, or any other fossil cetacean belonging to 

 the group of the former (Ziphius). 



I have endeavoured to point out another, scarcely less cha- 

 racteristic, formation of the cranium in our dolphin, as regards 

 the palate, which in my view is principally formed of the ptery- 

 goid bones, extending entirely over (in the proper position of 

 the animal, under) the palatal bones. Something approaching 

 to this reappears in the Hyperoodons. In all other whales the 

 pterygoid bones only occupy the posterior part of the palate. 

 This similarity would be still greater, were it not that I have 

 shown, that in the Hyperoodons the palatal bones extend to the 

 outermost part of the palate, and that the lacrymal bone is pre- 

 sent, which is wanting in the Gangetic dolphin, as well as gene- 

 rally in all toothed whales, owing probably to the peculiar cir- 

 cumstance of the confined extent of the orbits (see Memoirs 

 quoted before, pp. 375 and 93 respectively). A further confor- 



Ann. b Mag. X. Hist. Ser. 2. Vol.'w. ' 19 



