DE. J. MUEIB ON THE ANATOMY OF THE SEA-LION. 509 



of palate and lengthening of pterygoids go on apace. The tympanic bones descend and 

 become laterally compressed, whilst the carotic canal assumes a more vertical direction 

 posteriorly. Meantime the basisphenoid shelves upwards and forwards, the paramastoids 

 roughly bulging out. Growth of the occipital crest alters the back of the skull to a 

 kind of trefoil outline. Increment of the teeth widens the premaxillary region and 

 anterior nares. There is an upturning of the ascending ramus and an inflection of the 

 angle. The bones altogether become more massive and rugose. 



Fifth stage. As the skull ripens to old age, particularly in the male, all the charac- 

 teristic points of the fourth stage are carried out by excessive growth of processes, crests, 

 and other superficial developments of bony lines, spicules, and nodules. The cavity of 

 the eye looks forwards; the space behind for the temporal and masseter muscles 

 enlarging as fleshy bulk preponderates over cerebral character. 



It follows that all the aforesaid changes are an exact counterpart of what obtains in 

 the Gorilla. In early youth the brain is functionally predominant. Then the teeth 

 assume importance with a corresponding facial accession. Lastly, whereas brain-incre- 

 ment is apparently arrested, the muscles of mastication, those of the throat and neck, 

 indeed all connected with the head, and therefore involved in the organs of offence and 

 defence, paramountly swell in bulk and strength; nerves and blood-vessels augment 

 proportionally. Thus from the featureless skull is evolved the rugged, immense, and 

 terrible-looking carnivorous cranium peculiar to this and certain other genera of the 

 Eared Seals '. 



2. Spinal Column and TJwrax. 



a. Vertebrce. — Restricting myself to the Society's male specimen, its vertebral elements 

 were as follows:— 7 cervical, 15 dorsal, 5 lumbar, 4 sacral, and 8 caudal; or a total of 



39 pieces. 



The cervicals are all large relatively, the largest of the series. The first 5 or 6 dorsal, 

 from their greater spines and transverse processes, also seem large. The remainder of 

 the dorsals decrease in size as regards height and breadth. The lumbar vertebrae appear 

 of moderate size, the three hindermost being rather the stoutest. The 1st sacral is of 

 fair size; the remainder, with the caudal, form a graduated series, none of which are 

 large. The spinal column (46 inches long) does not seem to hinge on any particular 

 vertebra, all being equally movable by the thick cartilaginous intervertebral disks. 



The axis is the only cervical with a long spine. The first four retrovert neural spines 

 of the dorsal are longest and subequal ; there is no other prominent spine behind. All 

 the inferior processes of the cervical vertebrae, as De Blain^dlle ' has depicted, are stout 



> See AUen, as cited, for the genera Eumetopias, Zahphus, and Callorhimts. Dr. Gray, also, in several com- 

 munications to the Society^s Proceedings, has shown cranial alterations in some rarer forms, since the present 

 memoir was read. 



2 ' Osteogi-aphie,' plate vii. Atlas, part 2. 



VOL. VIII. — PART IX. Jnne, 1874. . * ^ 



