641 



bones ; there is a small vacuity in the thin basioccipital. The pterygoid processes are not 

 pierced for the ectocarotids. The posterior border of the bony palate is slightly concave : 

 the palatal portions of the palatines form together almost a square plate of bone. The maxil- 

 laries and premaxillaries form a short and narrow prominence in front of the orbits : the pre- 

 maxillaries do not reach the nasals. 

 From the Arctic Seas. 



Mus. South. 



3936. The jaws and some other portions of the skull of a species of Hooded Seal, 

 nearly allied to, if not identical with, the Cystophora cristata. 



The forms and proportions of the enamelled crowns of the teeth closely correspond with 

 those in No. 3935. The premaxillary bones present the same proportions; the antorbital 

 processes of the maxillary are relatively as feeble. The chief portion of the skull includes 

 the neural arches of the two anterior cranial vertebrae, the constituent elements of which are 

 numbered on coloured labels according to the TABLE OF SYNONYMS. The complexity of 

 the large turbinals is well shown in the maxillary portions of the skull. The teeth, which 

 are contiguous at this immature period, become separate from each other in the subsequent 

 growth of the jaws. 



From Newfoundland. 



Presented by Edward Eushworth, Esq. 



Genus Stenorhynchm 

 Dental formula : i -^-, c ^, m g^=32. 





3037. The skeleton of the Saw-toothed Seal (Stenorhynchus serridens). 



The vertebral formula is : 7 cervical, 15 dorsal, 5 lumbar, 3 sacral, and 1 1 caudal. The 

 metapophyses commence as tubercles outside the prezygapophysis on the second dorsal, are 

 distinct on the third dorsal, pass on the fore part of the diapophysis in the fourth, and con- 

 tinue rudimental as far as the tenth dorsal, on which they are well and distinctly developed ; 

 they again pass upon the outside of the prezygapophysis in the eleventh and twelfth dorsals, 

 and so continue throughout the lumbar, sacral, and anterior caudal vertebrae. The anapo- 

 physes are mere rudimental projections from the back part of the diapophysis. The trans- 

 verse processes of the axis are more developed than in the Phoca yreenlandica ; they show 

 as distinctly as in the other cervicals, but on a smaller scale, the pleurapophysial and diapo- 

 physial parts of the process. The cervical and anterior dorsal vertebrae have a hypapophysial 

 ridge, which, in the latter, is produced into a tuberosity : the lumbar vertebrae are charac- 

 terized by a pair of hypapophyses from near the hinder end of the centrum. These processes 

 indicate the great development of the anterior vertebral muscles called the psoae and longi 

 colli, and relate to the great share which the trunk-vertebrae take in the locomotion of the 

 Seal, especially on dry land. The cranium of this Seal is longer and more slender, and the 

 facial part tapers more gradually from the expanded cranium, than in the Stenorhynchus lepto- 

 nyx. The paroccipitals are small, but distinct. The petrosals are perforated posteriorly for 



4N 



