643 



the deepest. The sella turcica is very shallow, and is defined only by a posterior clinoid ridge, 

 between which and the platform for the optic cbiasma there is a long tract. The petrosals 

 terminate by obtuse subdepressed apices. The foramina lacera anteriora are of unusual size, 

 and appear to include the foramina rotunda : there is no ridge indicating the division between 

 the anterior and middle lobes of the cerebrum. The rhinencephalic fossae are small, but deep 

 and well-defined, and completely divided by a broad and thick crista galli. 



Presented by Thomas Chevalier, Esq. 



3940. The right moieties of the upper and lower jaws, with the teeth, of the Small- 

 clawed Seal (Stenorhynchus leptonyx). 



The outer alveolar wall has been removed, showing their fangs : these are single in the first 

 molar, double in the other four molars ; they are long in all, but are not made larger, by the 

 external cement, than the enamelled crown. 



Presented by Prof. Owen, F.E.S. 



3941. The first and second molar teeth, left side, lower jaw, of the Small-clawed 

 Seal (Stenorhynchus leptonyx). Presented by Prof. Owen, F.E.S. 



Genus Pelagius. 



Dental formula : t ?=?, e 1, , g=32. 



3942. A mutilated cranium of the Monk-Seal (Pelagius monachus}. 



As in the preceding species, the molar teeth, with the exception of the first in both jaws, are 

 implanted by two roots ; but their crown is short, subcompressed, conical, with a cingulum 

 strongly developed on the inner side, and developing a small anterior and posterior accessory 

 cusp. The entocarotid canal perforates the back part of the petrosal, as in the Phoca grcen- 

 landica : the ectocarotid does not pierce the pterygoid process. The upper contour of the 

 skull presents a sigmoid curve. The upper jaw is much less deep than in the Halicfuients, 

 No. 3943 ; the canines are relatively larger, and the nasal bones are much shorter. The 

 temporal ridges meet, and form a low sagittal crest over the posterior half of the frontals and 



parietals. 



Hunterian. 



Genus Halichcerus. 

 Dental formula : t f=|, t j=|, m gE|=34. 



3943. The skull of the Grey Seal (Halichoerus Gryphus}. 



This appears to be the original of the figure by Mr. Clift, in plate 27 of Home's paper in 

 the ' Philosophical Transactions ' for 1 822. It is certainly of the same species, and belongs 



4N 2 



