300 DR. E. EAT LANKESTER ON OKAPIA. 



any separate horn-cap or Cjiipliysis, but it may well be that the supraorbital boss 

 becomes more accentuated in the adult or old male. 



On the other hand, supposing our older specimen to be a female, it is possible that 

 the male has much more pronounced horns. It is impossible to decide whether our 

 large specimen is male or female, and we must await the arrival of furtlicr specimens 

 of the Okapi for information on the subject. 



The bases of the nasal bones are slightly thickened or swollen in the Okapi (as 

 shown in text-fig. 2, p. 284, otm.,and in Plates XXXI. & XXXII. ). This swelling 

 is thus in front of the region carrying the median boss of the Giraffe's skull, just as the 

 paired lateral swellings are anterior to those of the Giraffe. In Ilelladotherium there 

 are no lateral " bosses," but a median boss is present which is further back even than 

 in the Giraffe, and is distinctly parietal in position (text-fig. 4, p. 285, m.ji.h.). A 

 spiral arrangement of the hair of the Okapi's face corresponds in position to this slight 

 thickening of the nasal bones (see text-fig. 14, p. 299, d). 



There are those who would interpret the apparently hornless condition of Hellado- 

 therium and Okapia as due to a degeneration and loss of horns, present and well 

 developed in ancestors of these genera. On the other hand, it is possible to regard 

 tliese two forms (if actually proved to be hornless) as being in a primitive condition, 

 having developed the bosses or tumescences which are the first step in the history 

 of horns, but never having got any further. It does not seem to me possible to 

 decide between these two theoretical views ; but I am inclined, on account of the 

 absence of a deflection of the basicranial axis from the horizontal of the basifacial 

 axis or palatine, to infer that neither Okapia or its ancestors ever possessed large frontal 

 horns — not even horns so large as the parietal horns of Giraffa. The possession and 

 use of such horns (as distinguished from laterally-spread antlers) seems to involve the 

 mechanical necessity of a deflected cranial floor. Even Giraffa exhibits such a 

 deflection in small degree (see text-fig. 5, p. 286). 



V. — Characters presented by the Skin of the Okapi. 



The skin of the Okapi, when received in London, was in very good condition. The 

 paired ungual phalanges Avere still attached to the skin, but the horny hoofs had 

 been lost. The skin was softened and mounted for the Natural History Museum by 

 Mr. Rowland Ward. It must be remembered that no white man has as yet seen, or 

 at any rate given any account of, a living Okapi, nor even of the body of one freshly 

 killed. Nor have we received the skeleton of any part except the skull and hoofs. 

 Accordingly the proportions assigned to the various parts of the animal and the 

 carriage of its head and neck are, to a certain extent, conjectural and determined by 

 the proportions of the skin only, as thus received. The animal, as mounted, is shown 

 in the two drawings given in Plate XXX. with the natural colours. 



