1907.] RUDIMENTARY ANTLERS IN THE OKAPI. 133 



ankylosed with the frontal bone, but show an expanded base with 

 radiating ti-abecular structure of the bony material (see fig. 2, 

 PI. VII.) ; a pecuHarity of surface which is repeated by the enlarged 

 area of frontal bone upon which they rest — a condition which 

 occurs also in young Giraffes. As shown by the drawings in 

 Plate YII., there is no evidence in this ossicone of polishing or 

 sharpening of the apex. The rough longitudinal grooves and 

 furrows are continued to that region, and there are no transverse 

 fissures. A vertical section (fig. 7, Plate VII.) of the apical region 

 shows a very dense bony structure, but no trace of ingrowths 

 from the surface. We may take it that this ossicone was stiU 

 entirely covered in by the vascular living integument, as is the 

 ossicone in the Giraffe throughout life. It furnishes us with 

 a stage immediately antecedent to the fixation of the ossicone by 

 ankylosis to the frontal bone, and antecedent to the breaking 

 through of the integument by the apex of the bony cone. 



We may imagine the subsequent stages in the history which 

 connect this specimen with those figured in Plate VI. The rubbing, 

 polishing, and pointing of the ivory-like apex by use, the first 

 horizontal ingrowth of the lacerated investing integument, the 

 recession of that living investment after having established one 

 horizontal discontinuity or plane of disruption of the dense bone, 

 and the subsequent invasive ingrowth to form a second and by 

 repeated recession and ingrowth a third such plane of disruption, 

 and probably yet others. 



In conclusion, I would point out that it is quite conceivable 

 that this cutting off of a series of antler-like tips from the 

 ossicone of the Okapi, is a process independently set up in this 

 Giralfid animal, having a similar physiological explanation to 

 that which applies to the similar process familiar to us in the 

 Cervidse. 



The different views which may be entertained, in the present 

 state of our knowledge of the facts of embryology and eai-ly growth, 

 as to the inter-relations of the ossicones of the Giraffidfe, the 

 antlers of the Cervidse, and the bony horn-cores of the Bovidse, 

 are briefly stated in the preceding memoir on the " Origin of the 

 Lateral Horns of the Giraffe," and to this I would now refer the 

 reader. 



[April 1907.— I add here text-figures (54 & 55, p. 134) of the 

 ossicone of the specimen of Okapi brought home by Oapt. Boyd 

 Alexander from the Welle River and presented by him to the 

 National Collection. There are many interesting features about 

 the skin and skull which we owe to Capt. Boyd Alexander, and 

 these I hope to describe hereafter. The horn or ossicone is that 

 of an animal a very little younger than Majoi- Powell Cotton's 

 (as inferred from the dentition). It is intermediate in size 

 between that drawn in text- fig. 50 and that figured in Plate VII. 

 Its bony substance is much less dense and ivory-like than that of 



