132 PROF. E. RAY LANKESTER ON [Feb. 5, 



We have no knowledge or indication that the shedding of these 

 demarcated segments of the horn-tip is seasonal, nor indeed of 

 the actual occurrence of such a shedding. However, the animal 

 which is referred to in the explanation of Plate VI. as specimen A, 

 shows in both right and left horn-tips a well-marked concavity, 

 such as would correspond to the scar left by the " shedding" or 

 breaking off of a previously existing cap or segment of the dense 

 bony substance. In fig. 2, this is seen in a view of the mediad 

 (inner) face of the right ossicusp, and is marked x. In fig. 8 the 

 same cavity is seen (and marked x) in a view taken from in 

 front of, and somewhat above, the same horn-tip. 



It seems to me that we have in these appearances of the Okapi's 

 free or naked horn-tip (external termination of the ossicone) the 

 evidence of a process of the same physiological significance as 

 that seen in the seasonal removal of the antler in the Cervidae. 

 The continued contact of a deep tissue such as bone with the 

 infective material of the outer world cannot be tolerated : necrotic 

 organisms must effect a lodgment and gradually extend their 

 ravages into the whole tract of the ossicone, and even to the 

 bones of the skull. Accordingly, the exjDosed " tip " is cut off by 

 a bone-absorbing ingrowth of the living tegumentary tissue, and 

 the process of autotomy is active and i-ecurrent. In the Okapi 

 the process appears to be less elaborated and regularised than in 

 the Oervidse, and we do not know at present the details of its 

 commencement or its final development. It is, however, certain 

 that up to a late stage of growth, when the male Okapi is nearly 

 of full size, the ossicone has not penetrated the integument with 

 its tip, and that there is no indication of the polishing of the 

 ossicone's tip nor of transverse fissures caused by absorbent 

 ingrowths of soft tissue. This is demonstrated by the ossicone of 

 a male * Okapi of nearly full growth (the last molar of the upper 

 series being not yet in use and the premolars only recently 

 having superseded their deciduous fore-runners), which is illus- 

 trated in Plate VII. This specimen belongs to a very pei-fect 

 skeleton obtained, together with the skin, by Major Powell 

 Cotton in the Ituri Forest, which is now in the British Museum 

 (ISTatural History) at Cromwell Road. The ossicone figured is 

 that of the right side. It is larger than that of the left side, 

 weighing 3r45 grammes as against 28'15 grammes scaled by the 

 left ossicusp. This asymmetry of the ossicusps of the Okapi, and 

 a difference in the dii'ection of the slope of these structures when 

 right and left sides are compared, is to be observed in skulls of 

 adult male specimens, and was mentioned by me in my memoir 

 of 1901. 



The ossicones in Major Powell Cotton's specimen have not yet 



* Major Powell Cotton ascertained that this specimen is a male, by an examination 

 of the genital organs, and the skin prepared under his direction retains the external 

 genitalia. 



