REPORT ON THE SEALS. 23 



process of the superior maxilla. The posterior border of the hard palate was deeply 

 emarginate, and the posterior border of the vomer was visible between the two diverging 

 bones, though not to so great an extent in Weddell's Seal as in the other species. The 

 angle of junction of the two palate bones in the mesial line of the hard palate was in the 

 younger Stenorhynchus about opposite the last molar tooth, and in the older specimen 

 further back and almost on a line with the posterior border of the zygomatic process of 

 the superior maxilla. In Weddell's Seal again this angle was in a plane 1 1 mm. posterior 

 to the same process. In both specimens of Stenorhynchus two small triquetral bones 

 were situated at the antero-internal angle of the palato-maxillary suture, and in Dr. 

 Gray's figure of the skull procured during the voyage of the "Erebus" and "Terror" 

 a mesial triquetral bone is shown in the same region. 



The alisphenoid canal was absent. The tympanic bulla was almost hemispherical and 

 smooth in Weddell's Seal, and its antero-internal angle was truncated ; in Stenorhynchus 

 a keel-like ridge, not very elevated, was prolonged from the postero-external to the antero- 

 internal angle, the latter of which was pointed. The carotid canal was separated from the 

 foramen lacerum posterius in all three specimens by a distinct plate of bone as in the 

 Elephant Seal. A deep fissure also separated the tympanic bulla from the mastoid part 

 of the bone, and in it the stylo-mastoid foramen opened. The two optic foramina had a 

 common opening into the cranial cavity in both Leptonychotcs and Stenorhynchus. 

 The hamular process was barely visible in Stenorhynchus leptonyx, but in Weddell's Seal 

 it was present and directed outwards. 



The occipital condyles converged and met anteriorly in one skull of Stenorhynchus but 

 did not quite meet in the other, and in Weddell's Seal the cartilaginous covered surfaces 

 of the two were continuous. In Weddell's Seal the basi-occipital was thin and perforated 

 by a rounded hole, but in the other crania it was entire. A low par-occipital process was 

 present in Stenorhynchus, but was scarcely visible in Weddell's Seal. In both specimens 

 of Stenorhynchus the supra-occipital canals opened immediately within the posterior edge 

 of the foramen magnum ; in Weddell's Seal a single foramen only was present on the outer 

 surface of the bone close to the foramen magnum. 



The lower jaw in Weddell's Seal was proportionally more slender than in Stenorhynchus, 

 -which was in part due to the smaller size of the teeth, requiring a shallower alveolar 

 border, and in part to the more limited surfaces for the attachment of the masticatory 

 muscles. The body of the bone was straight and smooth, and with no eversion of the 

 lower border. The mandible had scarcely any ascent behind to the condyle, and had no 

 angle ; the subcondyloid process was absent in Stenorhynchus leptonyx, but in Weddell's 

 Seal it was a faint incurved tubercle. In Weddell's Seal the mandible was much more 

 slender than the lower jaw of Ommatophoca rossi, or Ross's large-eyed seal, figured in 

 pi. viii. of the Voyage of the "Erebus" and "Terror." 



Spine. — Vertebral formula, C 7, D 15, L 5, S 2, Cd 11 = 40. As the animal 



