1861.] 



DR. J. E. GRAY ON A NEW PILOT-WHALE. 



311 



of the Wliales which have heen cousidered species as mere sexes of 

 the same species, simply because the sjiecimen described in one case 



Upper surface of the skull of GloMocephalus incrassatus. 



happens to he a male and in the other a female. Thus Delphinus 

 micropterus is said to he the female of Ziphius sowerbiensis, for the 

 above reason ; but I have not heard that any new specimen has been 



