647 



* 



3962. The skull of the Harp-Seal (Phoca grcenlandica). 



It is the original of the specimen figured by Mr. Clift in Home's paper on the Skulls and 

 Teeth of Seals, in the 'Philosophical Transactions' for 1822, plate 28, and in his 'Lectures 

 on Comparative Anatomy,' vol. iv. tab. xix. The canines are short, but strong : the molars 

 small and set apart, with compressed pointed crowns, the principal cusp in all but the last 

 lower molar having one accessory basal cusp in front and two behind. The basioceipital is 

 an extremely thin plate, and shows a large vacuity in front of the foramen magnum. The 

 pterygoid processes are not pierced for the ectocarotids. The bony palate is terminated poste- 

 riorly by a transverse line ; the suture between the maxillary and premaxillary is obliterated. 

 The meatal portion of the tympanic is slightly bent, and directs the external auditory aperture 

 obliquely forwards and upwards. 



Hunter ian. 



3963. The partially separated bones of an incomplete skull of the Harp-Seal (Phoca 

 grcenlandica). 



The occipito-sphenoidal bone is formed, as in Man, by the coalescence of the basioceipital 

 and basisphenoid : it shows the bony tentorium, with the ossified posterior part of the falx : 

 the sella turcica is shallow, but well defined behind by the overhanging posterior clinoid pro- 

 cesses : the pterygoid processes are not perforated by the ectocarotids : the thin basioceipital 

 shows a slight vacuity. The left parietal is anchylosed to the temporal, in which the petrous 

 portion shows the deep transverse cerebellar fossa, and the carotid canal through which a 

 bristle is placed. In the right frontal may be seen the small rhinencephalic fossa, and the 

 very large proportion of the bone which contributes to the formation of the orbital and olfac- 

 tory chambers. The left frontal, maxillary and premaxillary bones have coalesced with the 

 prefrontals and vomer, which latter form a complete and very extensive bony septum between 

 the nasal passages : these are blocked up anteriorly by the sieve-like turbinals. The right 

 ramus of the jaw has been longitmdinally bisected, to show the dental canal and the sockets 

 of the teeth. The numbers upon the bones indicate their names according to the TABLE OF 

 SYNONYMS. 



Hunterian. 

 Genus Arctocephdw. 



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



3964. A mutilated cranium, wanting the lower jaw, of the Australian Ursine Seal, or 

 ' Sea-Bear ' (Ardoceplialus austrcdis}. 



The fractured frontal bones show the extension of the olfactory chambers exterior to the 

 rhinencephalic fossa. The border of the superoccipital, forming the upper part of the fora- 

 men magnum, shows the orifices of two venous sinuses. The posterior border of the bony 

 palate has an angular notch. The pterygoid processes are pierced for the ectocarotids. The 

 last molar is implanted by two diverging fangs. 



This skull was found eighty miles inland in South Australia. 



Presented by Dr. Hobson. 



