30 



THE VOYAGE OF H.M.S. CHALLENGER. 



their differential characters, I have drawn up a short account of these specimens on the 

 same lines as with the other genera described. I have also compared these Falkland 

 Island crania with the adult male skull of a Sea Lion brought by Dr. R. 0. Cunningham, 

 from Laredo Bay, Magellan Strait, 1 with another adult collected at Maldonado, Eiver 

 Plate, by the same naturalist, and with a third adult obtained in guano on the Chincha 

 Islands, off the coast of Peru, all of which specimens are in the Anatomical Museum of 

 the University of Edinburgh. The last-named skull was at one time in the collection of 

 Dr. M'Bain, and was described by him 2 as probably an example of the seal named by 

 von Tschudi and Peters, Otaria ullose. 



The principal dimensions of the crania are given in the following table : — 



Table IV. — Crania of Otaria. 



From the above table it will be seen that the adult crania from West Falkland Island 

 and Laredo Bay were in all their dimensions considerably larger than the Maldonado 

 and Chincha Islands specimens, and as all four crania had the basi-cranial synchondroses 

 closed, the question arises — Are the smaller skulls a different species from the larger, or are 

 they the females and the larger specimens the males of the same species ? In addition to 

 these differences in size the two larger crania, more especially the West Falkland specimen, 

 possessed lofty occipital, sagittal, and interfrontal crests, the latter of which was grooved 



1 Natural History of the Strait of Magellan, Edinburgh, 1871. 2 Journ. of Anat. and Phijs., vol. iii. p. 113, 1869. 



