Royal Physical Society. 425 



foramen. The orbito-sphenoids are so strongly compressed 

 in this specimen that the optic foramina have literally coalesced 

 into one. The posterior palatine foramina are small, and 

 chiefly confined to the palate bones. In Calocephalus vituli- 

 nus they are entirely formed in the palatine plates of the 

 superior maxillae. The anterior palatine foramina are much 

 smaller than in the common seal. The palate bone is a little 

 broader behind than in front, deeply notched and rounded. 

 The glenoid cavity is two inches in length, extending directly 

 outwards, and forms a deep, scooped-out space for the articula- 

 tion of the lower jaw. The malar bones are directed back- 

 wards until they approximate the outer edge of the articulate 

 surface. Two lines drawn from these points to the centre of 

 the incisor teeth will form two sides of a triangle, the third 

 side of which will be a line extending directly across the base 

 of the skull. The malar bones in the common seal do not pass 

 so far backwards, and the outline of the zygomatic arch and 

 base of the cranium is of an oval form. A striking peculiarity 

 of this skull, by which it can scarcely fail to be distinguished 

 from any other species, is an elevated sagitto coronal crest, 

 extending in a gradually arched form from the upper edge of 

 a parietooccipital crest, until it diverges by two slight ridges, 

 and loses itself into the post-orbital processes. This crest is 

 rather more than an inch high in the centre, and indicates the 

 presence of powerful temporal muscles in this species. The 

 nasal process of the superior maxilla reaches as far back 

 as the posterior extremities of the nasal bones. In the common 

 seal the nasal process does not pass so far backwards. This 

 character has been pointed out by Professor Owen as a special 

 osteological distinction between the lion and the tiger, and 

 may therefore be considered a useful one. The nasal bones 

 are separated behind by an acute-pointed triangular process 

 of the frontal bone, forming a double nasal notch, where the 

 nasal bones and nasal processes of the superior maxillae ter- 

 minate backwards. There are two very small external pro- 

 cesses on the anterior margins of the nasal bones. In the 

 common seal these external processes are well developed and 

 more acute, with two inner ones, smaller, and forming a short 

 triangle. At the anterior and under part of the nasal fossae, 



