138 Dr. J. E. Gray on the Species of Manatees. 



will separate the skulls of the two countries from one another. 

 Indeed the skulls of each kind are so variable that, after having 

 them laid out before me for two or three days, studying them 

 every now and then, and inducing two proficients in the study 

 of bones and in observing minute characters, to give me their 

 assistance, we came to the conclusion that we believed there 

 was no character, common to all the skulls of each kind, which 

 could be used to separate them. As a proof of the difficulty of 

 so doing, I may state that there was one skull in the series 

 which had been long in the Collection, and had been received 

 without any habitat, and neither of the three could decide to 

 which of the series this skull should be referred ; and it was not 

 until I accidentally observed the character derived from the 

 absence of the nasal bones in the African kind that this question 

 could be settled. It may be asked, Why was not the absence or 

 the presence of the nasal bones observed earlier in the examina- 

 tion ? The reply is easy: these bones are anomalous in the 

 genus, being small, far apart, and easily lost ; for they were 

 only present in one of the skulls, and their existence in the 

 other American skulls is only proved by the scar, or rather 

 groove which is left in the bones ; and though they are not 

 found in the skull of the African Manatee, we have no proof 

 that they are not free in the flesh of the nose in that species. 



The examination of a large series of skulls of the Bears ( Ursus) 

 and Paradoxuri shows how difficult it is to distinguish species by 

 the study of the skulls alone. Thus, when we have a series of 

 skulls of Bears from different localities, which, from their external 

 form and habits, are known to be distinct species, it is easy to say 

 which is the skull of U.tibetanus, U. syriacus, U.arctos, U.cinereus, 

 and U. americanus, when we have the habitat marked on each ; 

 but the true test of the power of distinguishing the one from the 

 other is to determine to what species a skull belongs, of which we 

 have no information as to its origin ; and we have several skulls 

 in the British Museum under these circumstances, and I cannot, 

 even with the best assistance at my command, determine to 

 which species they ought to be referred. And it is the same with 

 the skulls of the Paradoxuri. I have observed, in a large series 

 of skulls, that there is, in some genera at least, more difference 

 between the skulls of the same species from the same locality 

 than there is between two species from different localities which 

 are well established by external characters. 



If this is the case with skulls (and I particularly allude to 

 them, as they are generally regarded as the most characteristic 

 bones of a skeleton, and are therefore the bones most usually 

 studied by zoologists), how must the difficulty of distinguishing- 

 species with certainty be increased when we have only fossil bones, 



