OSTEOLOGY OF ANTARCTIC SEALS. 29 



Summary. 



The skulls correspond in their distinguishing characters from other Antarctic seals 

 to those tabulated by Sir WILLIAM TURNER in the Challenger Reports ( Voyage of 

 " Challenger" Reports on Seals, p. 66). 



With regard to the rest of the skeleton, one specimen alone does not provide 

 altogether sufficient evidence ; still, I note the following points which may be of interest 

 on further skeletons being brought home and examined : 



1. Much greater length-breadth index of vertebrae. 



2. Bifid character of 5th and 6th cervical spines, also present Ln type-specimen in 



British Museum. 



3. Sacral index. 



4. Scapular index. 



5. Humero-radial index. 



6. Non -articular area for ligamentum teres on head of femur continuous with non- 



articular neck. 



7. Ti bio-femoral index. 



NUMBER OF VERTEBRAE IN PHOCID^E. 



In the Resultats du Voyage du S.Y. " Belgica" : Zoologie, p. 7, Mr BARRETT 

 HAMILTON states that in most seals the numbers of the thoracic and lumbar vertebrae 

 appear to be usually 15 and 3 (5?), more rarely 14 and 6. In the Antarctic seals 

 without exception I have found the vertebral formula in the adult to be C 7 D ]5 L 5 

 S 3 Cd 10 or u . 



With a view to obtaining as large a number of specimens as possible, in order to 

 form an average, I have made a careful examination of the seal skeletons in the 

 University Museum here, the Museum of Science and Art of Edinburgh, British 

 Museum of London, and give a table of the vertebral formula in 47 specimens : 



Weddell seal : 27 with formula C 7 D 15 L 5 S 3 Cd 10 or n . 

 Crab-eating seal : 2 with formula C 7 D 15 L 5 S 3 Cd ]0 . 

 Sea-leopard : 2 with formula C 7 D 15 L 5 S 3 Cd 10 . 

 1 ,, C 7 D u L 6 S 3 Cd n . 

 Ross' seal : 1 with formula C 7 D 15 L 5 S 3 Cd 10 . 

 Sea-lion : 2 with formula C 7 D 15 L 5 S 3 Cd 10 . 

 Fur seal : 1 at C 7 D J5 L 5 S 3 Cd n . 

 Crested seal : 1 at C 7 D 15 L 5 S 3 Cd 10 . 

 Common seal : 2 at C 7 D 15 L 5 S 3 Cd n . 

 Elephant seal : 1 at C 7 D 15 L 5 S 3 Cd 10 . 

 New Zealand fur seal : 1 at C 7 D 15 L 5 S 3 Cd 10 . 

 West Indian seal : 1 at C 7 D 15 L 5 S 3 Cd 12 . 



(ROY. soc. EDIN. TRANS., VOL. XLVTL, 199.) 



