REPORT ON THE SEALS. 11 



and at its posterior border was doubly festooned, with a slight posterior process in the 

 region of the mesial palatal suture. The vertical plate of the palate bone extended 

 behind the posterior edge of the hard palate, and overlapped the outer surface of the 

 pterygoid. The hamular process was distinct and curved backwards and outwards. In 

 the older males the posterior border of the hard palate was in the same transverse plane 

 as the lower border of the articulation between the malar and the squamoso-zygomatic, 

 and a little in front therefore of the glenoid fossa ; but in the female and younger skulls 

 it was in a transverse plane, a little in front of this articulation. 



The posterior edge of the nasal septum did not in either sex extend so far back as the 

 posterior nares, and consisted of the posterior border of the vomer, which sloped down- 

 wards and forwards, and of an ascending vomerine crest from the palate bone, articulating 

 with the vomer in front of the truncated border. 



The alisphenoid canal was absent. The tympanic bulla was smooth and only 

 slightly elevated ; its general form was triangular, and prolonged into the greatly 

 elongated wall of the external meatus ; it was perforated at the postero-internal angle 

 of the base by the canal for the internal carotid artery, which looked almost directly 

 backwards and was quite distinct from the foramen lacerum posterius. When opened 

 into, the tympanic cavity was seen to consist of a chamber as big as a walnut, with which 

 both the external meatus and Eustachian tube communicated. At the posterior part of 

 the roof and immediately above the orifice of the meatus was a subordinate chamber of the 

 tympanum about the size of a hazel nut, and situated immediately to the outer side of the 

 petrous element ; it opened by a narrow fissure into the cranial cavity. As the tympanic 

 ossicles have already been so fully described by Mr. Doran 1 and by Professor Flower, 2 and 

 figured also by the former anatomist, it is unnecessary to redescribe them, as they correspond 

 so closely with the accounts which they have given. I need only state that the stapes 

 showed no trace of a division into crura. The optic foramina opened separately into the 

 cranial cavity, and between them was a mesial plate of bone continuous with a prominent 

 crista galli. The tentorium was partially ossified, although not so extensively as in some 

 seals. In the young skull, the cap of which had been sawn off for the removal of the 

 brain, the transverse diameter of the cranial cavity (148 mm.) was markedly greater 

 than the antero-posterior (127 mm.). 



The occipital condyles closely approximated in front, and in the males were separated 

 by a narrow groove. In the females the condyles were more widely divergent than in 

 the males. In one female where the process of maceration was carefully watched, a 

 broad plate of unossified cartilage, continuous with the basis cranii, extended backwards 

 along the inner border of each condyle for 29 mm. from the basi-occipital, so that the 

 foramen magnum was greatly diminished in size, as compared with a fully macerated 

 specimen ; in two of the males the corresponding plate of cartilage had undergone a 



1 Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. i., 1876. 2 Proc. Zool. Soc. Lond., January 4, 1881. 



