PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 419 
Pagophilus there is a less number of sacral vertebre than in the other 
subgenera, and the sexes are widely different in color, yet it is included 
by Professor Allen within the genus Phoca. Histriophoca fasciata can- 
not then be debarred on account of its possession of these same char- 
acters. It seems most logical to include the last-named species as a 
subgenus in Phoca, between Pusa and Pagophilus. To raise Pagophilus 
to the rank of a genus (as proposed by Dr. Gill), and to combine with 
it Histriophoca, would, in my estimation, make an isolation between 
them and Pusa which does not exist, while to make of each of the first 
mentioned a distinct genus would make the classification still more 
artificial. 
DESCRIPTION OF THE CRANIUM. 
The muzzle—The muzzle,* and indeed all of that portion of the skull 
which is anterior to the auditory bulle, is remarkably short. The 
breadth at the canines is about the same relatively as in P. fetida and 
P. grenlandica. The “palate” is rudely triangular, shortened in the 
anteroposterior direction, but little compressed laterally, and not deeply 
emarginate behind. The alveolar border is convex laterally and ven- 
trally, much as in Hrignathus barbatus. The distance from the distal 
end of the intermaxillaries to the pterygoid hamuli is less than one- 
half the Jength of the skull, and from the same point to the anterior 
edge of the auditory bullz is only 66 per cent. of the same length. The 
anterior nasal opening is elliptical, and corresponds closely to that of 
P. fetida, but is higher in proportion to the breadth. The posterior 
nasal opening is about one-half broader than deep. The narial septum 
is nearly complete, the length of the whole “ palate” being to the portion 
unoccupied as 66 to 10. The septum is, therefore, less developed than in 
P. grenlandica, and more than in P. fetida. The nasal bones are quite 
small, in length measuring less than one-fifth that of the skull; their 
breadth anteriorly is approximately one-half their length. The anterior 
border has the shape of the letter W with equal limbs. 
Orbital region.—The zygomatic processes of the maxillary are broad, 
long, and very thin. The fossa beneath the infraorbital foramen is un- 
usually deep, but does not involve the zygomatic process so much as in 
P. foetida. The temporal fossz are wide laterally. The zygomatic pro- 
cesses of the temporal bone are not so high as in P. fetida, but resem- 
ble more closely those of P. grenlandica. The interorbital ‘‘ bridge” is 
intermediate in width between that of P. vitulina and P. fetida. In the 
last-named species it is very narrow. The superorbital processes are 
rudimentary, but rather more developed: than in other representatives 
of Phoca. 
Brain-case, superior and posterior surfaces.—The brain-case is large, 
its length almost exactly equaling one-half that of the skull. Its lon- 
*That portion of the skull anterior to the base of the zygomatic processes of the 
maxillary. This term is used with such looseness that I regard it necessary to define it. 
