420) PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
gitudinal and transverse horizontal diameters are approximately equal. 
The convexity along tbe lines of the sagittal and coronal sutures is slight. 
The medial angle of the lambdoid suture is obtuse. The occipital makes 
an angle of about 45° with the base of the skull. The foramen magnum 
is an oblate ellipse. 
Brain-case, inferior surface.-—The paroccipital processes are wide 
apart, more so than in any other species of the subfamily, the distance 
between them being about the same as that between the meati auditorii. 
They are more strongly developed than in P. fetida, and less than in 
P. grenlandica. The auditory builz are larger than those of any other 
seal with which Iam acquainted. The anterior face is approximately 
at right angles to the main axis of the skull, and descends less perpen- 
dicularly than in other forms of the genus. The anterior extremity is 
obtuse, making the general outline rather more quadrilateral than tri- 
angular. The portion forming the inferior border of the meatus audi- 
torius is small, short, and convex, and is separated from the main por- 
tion of the bulla by a constriction, somewhat as in P. grenlandica and 
P. foetida. 
Mandible.—The lower jaw is short and small. The rami are narrow 
vertically, and in the aged female are flattened internally. The coro- 
noid process.is styloid, as in P. fetida and grenlandica, 
The teeth.—The dental formula was correctly given by Von Schrenck, 
as follows: 
3—3 1—1 5—5 
I. 2—2; C. 1—1; M. 5—5. 
The internal incisor is the smallest, the outer the largest. The ca- 
nines are small. The molars, also, are small, and approximately equal 
in size, although the fifth, and especially the first, are a little smaller 
than the others. The form of the roots is subject to variation, as will 
appear from the subjoined table: 
ROOTS OF THE UPPER MOLARS. 
| First. Second. | Third. | Fourth. | Fifth. 
| 
Won'Schrenck’s Seal ..s.2 che... -cscessencooece cceet | Single ..| Double .| Double | Double | Double. 
NOP B285 see lOVer Daye peds-nccsa=eeecee sion eee Single ..|..........| Double .) Double .| Double. 
NOI G64) hasan cu uentinees. chatentleweneebiananatane Single ..| Single ..! Double -| Double .| Double. 
ING: ODOR etic oct ene as eee Le Eee nee Single ..| Single a Single ..| Double | Double. 
| Sh RS i 1 
ROOTS OF THE LOWER MOLARS. 
| onl | 
| First. | Second. | Third. | Fourth. Fifth. 
Won Schrenck’s Seal 22225500 cjscecs caccre cease Single mi Double -| Double | Double .| Double. 
WNosszeb.; ‘PloverpBay ii 2st cs csscdesseecweee eens] anse neeeae PinGlOl == |p ae eaeee Single -. 
INO; ML BBG4 > 8258 phe ees Sin Navan sae tes ee eee ene Single ..| Single ..| Single ..| Single -.| Donble. 
INO; 18863) Jccsscspaceaccswsssscevet ere srizcscetces Single ..| Single ..| Single ..| Double .! Double. 
A fourth molar, single-rooted, is present in sides of the lower jaw in this speci- 
men. 
