649 



required the elevation of the temporal ridges into a parietal crest, nor any considerable develop- 

 ment of the occipital ridge. The boundary of the large mastoid is well shown in this skull, 

 together with the share which the paroccipital takes in the rough muscular ridge external to 

 the petrosal. The middle surface of the basioccipital is less carinate than in the male. The 

 entry of the carotid canal in the petrosal is more distinct from the jugular vacuity. The 

 broad superorbital processes of the frontal are less angular. The canines and external incisors 

 of the upper jaw are smaller, in comparison with the molars. The first and second incisors 

 have bifid crowns. The angle of the lower jaw is produced and bent inwards more than in 

 the male. 



Presented by Admiral Beaufort, C.B., F.R.S. 



3969. The skull of a female Leonine Seal (Otaria leonina). 



The teeth have been removed from the right side of the upper and lower jaw, and are 

 separately displayed. 



Hunter ian. 



3970. The cranium with the hyoidean arch, but wanting the lower jaw, of the Leonine 

 Seal (Otaria jubata}. 



In this specimen processes are developed into the temporal fossae not only from the frontals, 

 but also the parietals, and' would seem to have divided the great crotaphite muscle into three 

 masses. The calvarium has been removed, showing the two superoccipital sinuses descending 

 to the condyloid fossae ; the broad arch of the bony tentorium ; the ridge on the inner side 

 of the parietal, dividing the middle from the anterior lobe of the cerebrum, parallel with the 

 external ridge projecting into the temporal fossa, and the upper and posterior surface of the 

 superior turbinals occupying that part of the olfactory fossa which overarches the rhinence- 

 phalic chamber : this is divided by a broad crista galli. There is a large oblong vacuity at 

 the outer and posterior side of the nasal passages between the frontal, presphenoid, palatine 

 and maxillary bones : the same vacuity being repeated in each of the skulls of the Otaria 

 leonina, indicates that it is natural, and that it is closed by membrane in the recent animal. 

 There is a smaller vacuity in the corresponding part of the skulls of some other species of 

 Seals. 



Presented by Admiral Beaufort, C.B., F.R.S. 



3971. The vertically bisected skull of a male Otaria jubata. 



The posterior part of the falx and the whole of the tentorium are ossified. The super- 

 occipital sinus, commencing by a common aperture at the hinder extremity of the longitudinal 

 sinus, diverges on each side into the substance of the exoccipitals, and terminates in a deep 

 and wide fossa on the inner side of the condyle, from which fossa one canal leads backwards 

 to open external to the condyle, and another downwards and inwards to terminate in the fora- 

 men jugulare. A bristle is inserted into the parietal venous sinus. The bony tentorium 

 terminates anterior to the petrosal, which has an obtuse expanded inner apex, and shows no 

 petrosal pit. There is no Gasserian fossa. A ridge divides the foramen ovale from the fora- 

 men rotundum. The sella turcica is broad and shallow : it is defined by posterior clinoid 



4o 





