306 DR. E. RAT LANKESTER ON OKAPIA. 



Okapi. TIic fine bony cones, three inches long, which have made their appearance in 

 the Brussels skull (see text-fig. 15, p. 304) show no suture at their base, or any indication 

 of origin as distinct cap-like structures. For all that one can see, they may be direct 

 outgrowths of the frontal bone itself. Curiously enough, the point and posterior 

 margin of the bony cusp is polished as though it had protruded through the skin like 

 a cervine antler. The point is separated by a suture from the rest of the ossicusp, 

 forming a small terminal cap of bone a third of an inch in depth. This curious 

 structure, as well as a possible second suture a little lower down the ossicusp, 

 was pointed out to me by Dr. Forsyth Major. These appearances will be figured 

 and discussed in that gentleman's memoir on the Brussels specimens. It is clear 

 that we must wait for specimens of intermediate growth in order to form any 

 conclusions as to the mode of growth of the Okapi's ossicusps. It seems not 

 improbable that when we have those facts, important light will be thrown on the 

 relationships inter se of the various cranial ossicusps of Giraffidse, Cervicornia, and 

 Cavicornia. 



It is perhaps worth while calling special attention to the fact that Sir Harry John- 

 ston's larger skull of Okajna is very nearly as long as the adult male skull recently 

 acquired by the Congo State Museum ; there is only two millimetres difference in the 

 length from the occiput to the end of the nasal bones. Sir Harry's specimen is actually 

 broader by three and a half millimetres than the Brussels skull. And yet Sir Harry's 

 specimen has no ossicusps and shows the fronto-parietal suture clearly, whilst the 

 Brussels specimen has bony ossicusps three inches long and absolutely continuous 

 with the frontal bone, whilst the fronto-parietal suture is obliterated. Perhaps the 

 difference of form and the late appearance of the ossicusps in our larger specimen as 

 compared with the Brussels skull are due to the fact that our specimen is a female, 

 whilst (according to direct testimony of the senders) the Brussels skull is that of a 

 male. We have yet to hear further details as to the bony horn-cores reported by 

 Dr. Forsyth Major as embedded in the skin of the head of the second Brussels 

 specimen, which is known to be that of a female, and of which neither skeleton nor 

 skull accompany the skin. These detached horn-cores of the female are stated by 

 Dr. Forsyth Major to be two and a half inches long. 



A further point to which I may draw attention is that there is considerable want of 

 symmetry in the Brussels skull, in so far as the size of the bony horn-cores is concerned. 

 One is distinctly larger than the other. Now it is a curious fact that the skin of the 

 head of our Okapi shows, as I have pointed out (text-fig. 14, p. 299), a marked 

 asymmetry in the hair-whorls of the frontal region. Until the hair-whoiis of Mam- 

 malia have been more closely studied, it will not be possible to say what amount of 

 significance should be assigned to this asymmetry. But it seems to me to offer an 

 interesting field for enquiry. 



