206 FAMILY OTARIID^. 



poral bullae and the os petrosuin. The upper surfaces are very 

 much alike, and the orbits are very large and of the same size. 

 The lower jaws are very similar; but the callosity of the Falk- 

 land Island specimen is rather longer, and the crown of the teeth 

 is longer and rather more slender the crown of the ]S"ew-Zea- 

 la.nd specimen being as long as broad, that of the Falkland 

 Island specimen being one-third longer than broad."* I cite 

 the differences here noted by Gray to show how trivial are the 

 grounds of separation. A skull of each of the supposed species 

 only is here compared. The differences are just such as occur 

 between undoubted specimens of CaJlorlmius nrsinus, no two of 

 which, even of the same age and sex, can be compared without 

 observing differences, while there is no difficulty in selecting 

 specimens that are very unlike in characters that have been 

 taken, in discussing other species of this group, as having great 

 significance. Again Dr. Gray, in comparing his Gypsopkoca 

 tropicalis from ISTorth Australia with Peters's Arctoplioca argen- 

 tata and A. pliUippiiivovn Juan Fernandez and Masafiiera, says: 

 '^ These three skulls have nearly the same teeth, and appear to 

 me to belong to one group 5 but whether they are three distinct 

 species (two from the west coast of South America and one from 

 North Australia) I will not attempt to determine, as I have only 

 seen the skins and skulls of the one from the latter region ; but 

 they are all Fur-Seals and may be distinct."t Dr. Gray says 

 his genus Gypsoplwca " is most like Arctoplioca in the position 

 of the teeth; hut the palate is miicli narrotcer, the face shorter, and 

 tlie hinder part of the slmll much larger and more ventricose''^ ;X but, 

 as Clark has shown, and as is evident from Gray's figures, Gyp- 

 sophoca was based on a young skull, and young skulls of Otaries 

 differ from adult ones of the same s]3ecies in just these characters. 

 It may here be noted that in several instances the so-called " spe- 

 cies" of Fur Seals differ from others recognized by the same 

 authors only through differences that can be demonstrated to 

 be, in other well-known allied species, simply sexual. Hence, 

 until writers on this group have learned to discriminate the 

 sexes, and to make due allowance for the great changes in' 

 contour and details of structure that result from age in the 

 skulls of Otaries, we can hardly hope to have the subject of 

 species placed on a proper basis. 



* Hand-List, p. 36. 



+ Hand-List, p. 28; iirst printed in Proc. Z06I. Soc. Lond., 1872, p. 661. 



t Proc. Zool. Soc. Lond., 1872, p. 659. 



^Ibid., 1873, p. 759. 



