394 



PROF. FLOWER ON A NEW 



[May 



the nares is thrown exceedingly to the left side. So far, however, 

 there is nothing essentially different from Hyperoodon rostratus. It 

 is in the region immediately in front and to the side of the blow- 

 holes that the great difference is seen. This part in H. rostratus 

 is characterized by the very prominent maxillary crests, the inner 

 surfaces of which rise vertically from the outer border of the great 

 "infraorbital"' foramen, the two opposed surfaces being nearly 

 parallel with one another, or even slightly hollowed, so that their 

 summits have a tendency to inversion. Although the amount of 

 elevation to which the corresponding crests might have attained in 

 the new specimen cannot be satisfactorily ascertained, as their surfaces 

 have evidently been subjected to the attrition previously alluded to, 

 it is perfectly evident that they differed greatly in form from those 



Fig. 2. 



Side view of craniuai of Hijperoodon planifrons. 



ofU. rostratus, as the still unworn (because protected) inner surfaces 

 slope gently outwards and upwards from the edge of the foramen, 

 and the crests therefore, though with a base even broader from side 

 to side than in //. rostratus, must have been low and rounded and 

 quite devoid of any tendency to inversion. Another great difference 

 (better seen in the side view, fig. 2) is that the crests do not sink 

 abruptly at their hinder end, leaving a deeply depressed surface of the 

 maxillary bone intervening between them and the occipital elevation, 

 but they are continued backwards, above the temporal fossa, and so 

 pass gradually into the occipital crests, forming a continuous outer 

 wall to the great basin in which the blowholes are placed, which is 

 completely interrupted in //. rostratus. Among minor differences, 



' Or tbe foranicn corresponding to the infraorbital in man, in transmitting 

 the branch of tbe fifth pair of nerves that supplies the cheek and upper lip, but 

 not infraorbital in position in the Cetaceans. 



