( 187 ) 



VIII. — Scottish National Antarctic Expedition : Osteology of Antarctic Seals. By 

 Robert B. Thomson, M.B., Ch.B., University of Edinburgh. (With One Plate.) 



(MS. received April 26, 1909. Read July 4, 1909. Issued separately October 12, 1909.) 



Through the courtesy of Dr W. S. Bruce, the leader of the Scottish National 

 Antarctic Expedition, and of the late Professor D. J. Cunningham, the skeletons of the 

 seals collected in the Antarctic during the voyage of the Scotia have been placed in my 

 hands for study, and I wish to express my gratitude to these gentlemen for their great 

 kindness in placing all the necessary requirements at my disposal. I also wish to state 

 that Dr Bruce has given to the Museum of the University of Edinburgh a choice of 

 the various skeletons, which, together with the specimens already obtained, will form 

 a comprehensive and almost unique collection of the Antarctic seals. 



The seals obtained during the stay of the Scotia in the Antarctic seas numbered 

 forty-four, and embrace all the Phocidse found there, with the exception of the 

 elephant seal. Of the forty - four, thirty-four are Weddell seals (Leptonychotes 

 Weddelli) ; four are saw-toothed seals (Ogmorrhinus or Lobodon carcinophaga) ; 

 three are leopard seals (Stenorliyncus leptonyx) ; one is a sea-lion (Otaria Jubata) ; 

 while two are Ross seals (Ommatophoca Rossi). 



A most careful account of date of capture, sex, probable age, full measurements, and 

 weight was recorded in a special log-book. In some cases the skeletons were cleaned 

 by immersing the carcases beneath the ice, when amphipods and cushion-starfish did 

 the work ; in other cases the carcases were conveyed in special tanks and cleaned after 

 their arrival home. 



The osteology of the more common species of the Phocidse represented in this collec- 

 tion, such as the Weddell seal, saw-tooth seal, sea-lion, and leopard seal, appears to have 

 been pretty fully worked up, and especially so in a minute and careful description by 

 Principal Sir William Turner ; for the present, therefore, the endeavour of this work is 

 to present a detailed description of the Ross seal, as I have not been able to find such 

 of the skeleton of this species, with the exception of the skull. In the second place, I 

 purpose making a summary of the large collection of other seals with regard to such 

 points as dentition and vertebral formula, since the collection is large enough to obtain 

 a satisfactory average. 



Ross Seal (Ommatophoca JRossi). 



The first specimen of Ommatophoca was obtained by Sir James Ross in 1840, in 



the pack-ice in the Ross Sea, and is now preserved in the British Museum as the 



type-specimen. I am indebted to the authorities of the British Museum and to 



Dr 0. Thomas for the privilege of examining this specimen for purposes of com- 

 TRANS. ROY. SOC. EDIN., VOL. XLVII. PART I. (NO. 8). 28 



