REPORT ON THE SEALS. 9 



diameter was about four-fifths that of the entire distance, whilst in the female (/) and in 

 the youngest skulls, both male and female, the orbital diameter was almost equal to the 

 distance from the cranial box to the antorbital process, so that the orbital process of the 

 malar bone, was almost in the same transverse plane as the anterior wall of the cranial 

 box, instead of being considerably in front of it as in the older male crania. The 

 temporo- zygomatic fossa had therefore a greater relative antero-posterior diameter in 

 the adult males than in the female and in the younger skulls of both sexes, and this was 

 correlated with a greater elongation of the constricted part of the frontal region. The 

 zygomatic process of the temporal was bent abruptly upwards behind the orbital 

 process of the malar, as far as, or almost as far as its tip, and the two bones formed a 

 lofty process in this region of the face. The antero-inferior angle of the parietal bone 

 articulated with the alisphenoid. 



The nasal bones in both sexes were relatively short, triangular, and with the apices 

 received between the anterior diverging borders of the frontals ; the base was forwards 

 and with a notch marking the interval between the two bones. The anterior edge of 

 the mes-ethmoid was vertical, and grooved for the reception of the nasal cartilage ; in the 

 males it came forward as far as the anterior border of the nasals above, but in the females 

 not quite so far forwards ; whilst below it was lodged in the bottom of the spoutdike 

 vomer, the anterior end of which projected horizontally for some distance beyond the 

 mes-ethmoid and the anterior border of the nasals. The premaxillary bones consisted 

 only of a horizontal part, which was prolonged far in front of the anterior nares, so that 

 in the males this bone had the extreme length of about 140 mm., and in the largest 

 female 69 mm. In the larger skulls each bone possessed a premaxillary tubercle above 

 the incisor teeth. The anterior end of the beak was broadly truncated in the males, 

 and the superior maxillse with their canines were almost in the same transverse plane 

 as the incisor teeth. In both sexes the upper surface of each premaxilla was almost 

 horizontal and fitted on to the inner surface and anterior end of the superior maxilla ; 

 it bifurcated posteriorly, the inner fork articulating with the outer side of the anterior 

 end of the spoutdike vomer, whdst the outer broader fork rested on the horizontal 

 portion of the superior maxilla. As the premaxilla did not possess an ascending jjart it 

 did not enter into the formation of the lateral boundary of the anterior nares. 



The anterior nares were wide, and owing to the vertical direction of the mes-ethmoid 

 and their steep and almost vertical lateral boundaries, were in the vertical transverse 

 plane of the face almost on a level with the front of the zygomatic arch. They were 

 bounded above by the nasals, laterally by the nasal process of each superior maxilla, 

 and below by the vomer, superior maxdlas and premaxilla^, whilst the interval between 

 the mes-ethmoid and outer wall of each chamber was filled up by the highly subdivided 

 maxfilo-turbinal, which came forwards so as to be in the plane of the opening. In 

 Table I. the height and width of the anterior nares in the two sexes are given, from 



(zool. cball. exp. — part Lxvui. — 1887.) Yyy 2 



