DE. J. MURIE ON THE ANATOMY OP THE SEA-LION. 513 



=2*0, 0*9, 1-0, 08, 0"8, 0*95, 1*1, 1-6. Thus these bones present the same relations 

 as regards size in the young and older animal. It is not so, however, with the cartilages, 

 which in the young Otary are each equal to half the length of the bone, but in the 

 adult no more than a third. 



The sternal cartilages are thick, long, and flexible; but the last three are shorter 

 than the others, and comparatively free. The first cartilage articulates with the prse- 

 sternal bony facet. The second, third, and fourth are attached to the middle of the 

 intersternal cartilages. The fifth, sixth, and seventh join the intersternal cartilages 

 more obliquely, and are inserted chiefly into the hinder corners of the 4th, 5th, and 

 6th sternal bones. The eighth cartilage is fixed to the rounded postero-outer border 

 of the seventh bone ; the 9th to the middle of the cartilage. 



The cavity of the thorax and abdomen enclosed by the ribs, is long, deep, and narrow, 

 according as the ribs are expanded or otherwise, heart-shaped, =22 inches long. The 

 ribs either stand out or are flattened. This is chiefly permitted by the looseness of the 

 cartilaginous and ligamentous union, also length and flexibility of the sternal cartilages. 



3. Bones of the Extremities. 



a. Pectoral Limb. — Scapula. This has not the arched or semilunar shape of the 

 Common Seal, but is a broad irregularly trapezoidal thin bone. It measures in our 

 specimen 6-5 inches from the glenoid head (the cartilage in situ) across to the middle 

 vertebral or posterior border, and it is 8 inches in diameter between the superior and 

 inferior angles. The spine is of moderate nearly uniform height, and possesses a 

 downward slant, overarching very slightly the infraspinous fossa. It is carried onwards 

 to within J an inch of the glenoid cavity, whence an acromion process rather broader 

 than the spine itself reaches almost to the articular fossa. In the recent state a 

 ligament converts this acromial arch into a foramen. The glenoidal cavity is shallow 

 and more oval in shape than in Phoca vitulina. The neck is very short, broad, and 

 stout. Only a rudiment of the coracoid process is present. The supraspinous fossa 

 occupies the upper three fourths of the bone 1 . A slightly raised ridge proceeds from 

 the upper third of the neck backwards and towards the superior angle, dividing the 

 supraspinous fossa into two shallow concavities. The narrower, but deeper, infraspinous 

 fossa has the oblique ridge and groove for the teres major distinctly marked. The 

 space lodging the infraspinatus muscle is hollow, and not convex. 



Humerus. Figured in three different views by De Blainville {op. cit. pi. viii.), is 

 short, stout, and peculiar-looking from the great development and prominent nature 

 of the deltoid eminence. The greatest length of the bone in a straight line is 6 \ inches, 

 being \ of an inch less than the radius, and If inch shorter than the ulna. The 



1 Vide Cuvier, ' Ossemens Fossiles,' torn. v. pt. i. p. 224, and De Blainville, op. cit. text, torn. ii. p. 23, Atlas,' 

 vol. ii. pis. iii. & viii. 



