1871.] PROF. FLOWER ON PHOCA HISPIDA. 511 



It must first be mentioned that it is that of a very aged animal, 

 as shown by the condition of the cranial sutures and the teeth. Of 

 the latter some had been lost during life, and others after the pre- 

 paration of the skull ; and all those that remain are worn down nearly 

 to the level of the alveolar border, so that they are of little use for 

 identification. As far, however, as their characters serve, they agree 

 with those of other specimens of P. hispida with which I have com- 

 pared them, being rather smaller than those of P. vitulina, and 

 having the long diameter of the molars in a Hue with the alveolar 

 border, and not oblique, as is almost always the case with the latter. 



The deep angular emargination of the hinder border of the bony 

 palate at once distinguishes this skull from that of either P. barbata 

 or P. grcenlandica ; so that P. vitulina is the only one with which 

 it could be confounded. It is distinguished from this species : — 



1st. By its small size ; for though Seals have a considerable range 

 of variation in this respect, all the perfectly adult examples of vitulina 

 I have met with are considerably larger than the present specimen, 

 ranging from 7'7 inches (196 millim.) to 8*5 inches (216 millim.). 



2nd. By the narrowness of the upper surface of the skull between 

 the orbits, and also of the nasal bones. Different specimens of P. 

 vitulina vary much in this respect, but they are always broader in 

 this region than P. hispida. 



3rd. By the presence of a rudimentary anteorbital process on the 

 maxillary bone, which is always absent in P. vitulina. 



4th. By the pointed form of the upper end of the ascending pro- 

 cess of the prsemaxilla, which is in contact for a considerable space 

 with the nasal — whereas in P. vitulina this process is usually more 

 or less truncated above, and is completely separated from or only 

 just touches (at one point) the nasal. Both P. barbata and P. 

 grcenlandica resemble P. hispida in this character. 



5th. By the posterior palatine foramen being situated on or be- 

 hind the maxillo-palatine suture. In P. vitulina it is placed in the 

 maxillary bone altogether in front of the suture. This and the last 

 are important diagnostic characters, being constant and readily re- 

 cognized. 



6th. By the wide interval on the upper surface of the cranium 

 between the ridges which bound the temporal fossa, whereas in old 

 specimens of P. vitulina these ridges meet at the vertex. 



7th. By the larger size of the unossified spaces in the base of the 

 skull lying to the inner side of the auditory bullae. 



8th. By the comparative shallowness (vertically) of the hinder 

 portion of the ramus of the mandible, occasioned by the smaller 

 development of the region of the angle, and especially of the anterior 

 margin of the coronoid process, which is altogether weaker than in 

 P. vitulina. 



9th. By the form of the inferior margin of the ramus of the 

 mandible, which in the present species (as in P. barbata and grcen- 

 landica) has a conspicuous expansion inwards a short distance behind 

 the symphysis, which causes the edges of the rami to continue more 

 or less approximated for nearly half the length of the lower border ; 



