642 



the entocarotids ; the pterygoid processes are not perforated for the ectocarotids. The tem- 

 poral ridges meet upon the sagittal suture, but do not develope a crista. The malar bones 

 are slender, strongly curved, suspended in the middle of the zygomatic arch, bifurcate poste- 

 riorly, the upper prong rising to form with the zygomatic process of the squamosal, the post- 

 orbital process. There is no corresponding process from the frontal. The antorbital process 

 of the maxillary is small, hut distinct. The premaxillaries are narrow and slender, but do 

 not reach the nasals. The posterior border of the bony palate is terminated by a deep semi- 

 elliptic notch. The digits of the fore paddle progressively decrease in length from the first 

 to the fifth, but the first, or ' pollex,' preserves the normal inferior number of phalanges : its 

 metacarpus has twice the length and thickness of that of the index, and the proximal phalanx 

 has nearly the same proportions. In the hind paddle the first and fifth digits are the longest, 

 the middle digit is the shortest, but the first, or ' hallux,' has but two phalanges as usual. 

 The specific distinction of this Seal is chiefly shown by the structure of the molar teeth. The 

 three anterior molars on each side of both jaws are four-lobed, having two lobes behind the 

 principal one, and one in front of it ; the remaining molars, two on each side of both jaws, 

 are five-lobed, the principal lobe having one smaller lobe in front, and three lobes behind it. 

 These lobes in all the molars are separated by as deep notches as the fewer lobes are in the 

 teeth of the Stenorhynchus leptonyx, but their summits are less acute. 



The skeleton was prepared from a specimen obtained in a high latitude in the Australian 

 Seas, during the Antarctic Expedition. 



Presented by Robert M'Cormick, Esq., F.R.C.S., Surgeon to H.M.S. Terror. 



3938. The skull of the Small-clawed Seal (Stenorhynchus leptonyx). 



This is the original of Mr. Cliffs figure, published in Home's papers in the ' Philosophical 

 Transactions ' for 1822, pi. 2y, and in his ' Lectures on Comparative Anatomy,' vol. iv. pi. 20. 

 It was obtained from the island of New Georgia, near the Antarctic ice. It agrees in general 

 form and characters with the skull of the Stenorhynchus serridens, but the lower fourth of 

 the malar is proportionally longer, extending nearly to the glenoid cavity : the ascending pro- 

 cesses of the premaxillaries are relatively longer : the lower border of the mandibular ramus 

 is straighter, and the symphysis shorter and more abruptly bent upwards : but the chief 

 difference is in the crowns of the molar teeth, which are deeply cleft into three cusps, the 

 middle one being the longest. The first molar above has a small accessory tubercle on the 

 inner expanded part of the cingulum, and the cingulum is well developed at the same part 

 of the crown of the three succeeding molars : it is wanting in the lower molar teeth. All the 

 molars are two-fanged, but the fangs of the first are connate in both jaws. There is a single 

 superoccipital venous canal, which opens within the border of the foramen magnum : the 

 ligament completing the contour of the orbit is preserved on the right side. 



Presented by William Keane; Esq. 



3939. A mutilated cranium of the Small-clawed Seal (Stenorhynchus serridens). 



The calvarium has been removed, exposing the capacious cerebral chamber and the thinness 

 of its lateral walls. The basioccipital shows two smooth depressions, the anterior one being 



