Dr. J. E. Gray on the Genus Hoperoodon. 221 



both species ; and secondly, the structure and form of the two skulls 

 is so different, that it is much more likely that they should be refer- 

 able to two very distinct genera than to species of the same genus. 



I may state that I have examined four skulls of the H. latifrons, 

 and Professor Eschricht has another. 



There is a skeleton with the skull of an adult animal of this species 

 in the College Museum at Edinburgh, which was obtained from the 

 Frith of Forth on the 29th of October, 1839. Mr. William Thomp- 

 son (Ann. and Mag. Nat. Hist. 1846, vol. xvii. p. 153) informs us that 

 this specimen was a female 28^ feet long, accompanied by a young 

 male. So there can be little doubt that there are females of Hy- 

 peroodon latifrons as well as males. 



It appears to be a northern species. As I have seen specimens from 

 Greenland, the Orkneys, and the Coast of Lanarkshire, this is the 

 most southern example that has yet occurred to me. It is also pro- 

 bably a much larger species than Hyperoodon rostratum, as the skull 

 from Greenland in the Newcastle Museum is 92 inches long, while 

 the largest skull of H. rostratum that has come under my observa- 

 tion does not exceed GO or 65 inches. 



It is only necessary to examine the figure of the two skulls of 

 Hyperoodon rostratum and H. latifrons in the Plate to the * Voyage 

 of the Erebus and Terror,' to see how exceedingly different they are 

 from each other, not only in the form of the skull, but also in the 

 form of the lower jaw. The skull of H. latifrons not only differs 

 from that of H. rostratum in the thickness and solidity of the frontal 

 crest of the maxillary bones, but in the crest being much higher than 

 the hinder part of the skull ; while in all the skulls of H. rostratum 

 I have seen, the crest is of the same height with the frontal ridge. 



As regards Hyperoodon rostratum, Mr. Beardsworth states his 

 specimens to be a female and a young female. The specimen which 

 was shot at Weston-super-Mare, Mr. Crotch informs me, is a female. 

 I may also observe that the specimen of this species described by 

 Mr. William Thompson in the Annals and Mag. of Nat. Hist. 1846, 

 vol. xvii. p. 150, is said to be a male : its skeleton is now in the 

 Belfast Museum. So there are certainly male and female of this 

 species also known. 



Mr. Crotch has furnished me with the following measurements of 

 the female specimen taken at Weston-super-Mare, which was exhi- 

 bited at Bristol : — 



feet. in. 



Total length 26 



From posterior origin of dorsal fin to insertion 



of the tail 6 



Dorsal in width at base 1 II 



in height 1 5 



Tail in diameter 7 



in depth 2 



Cloaca to insertion of tail 5 3 



Length of cloacal fold 2 



From anterior of cloaca to pectoral 8 6 



