DR. J. MURIE 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 isan 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 
Fared Seals’. 
2. Spinal Column and Thorax. 
a. Vertebre.—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 vertebre 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 vertebr, as De Blainville* has depicted, are stout 
’ See Allen, as cited, for the genera Humetopias, Zalophus, and Callorhinus. 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 ¢Ostéographie,’ plate vii. Atlas, part 2. 
VOL. VIIIL—PART IX. June, 1874. 4B 
