Explanation of PLATES 13-17. 



PLATES 1:^-17. 



Tlie fitiiiros in Tlatos 1 :' — 17 show the dorsal views of fiftc^en skulls of tlie Okapi in 

 the Uritisli ]\rnseiiin, the ^Museums of Edinbnvgh, Tervneren, Itonie, ^Madrid, Genoa, and 

 I'ai'is, and the private collections of Major Powell-Cotton and tlie Jlon. Walter Rothschild, 

 drawn mainly from ]ihotoo'vaphs taken with a telephoto lens, with th(> hasicranial axis of 

 the sknll set normally to the line drawn from the centre of the sknll to the centre of 

 the lens. 



With a view to facihtatinti- a compaiison of the l(>n^-th of the nasal region of the 

 various skulls with the postoi'bital breadth, for the purpose of deciding whether two 

 tyjies of skull, "broad" and "narrow," can be distinguished, dotted lines have been 

 drawn in the figures to explain the method of ol)taining the ratios mentioned in the 

 legends Ijeneath the figiu'cs. The distance MN is the distance from the front of the 

 suture between the nasal and premaxillary bones to the outei' end of the suture between 

 the nasal and fi'ontal bones, that is, to the foremost ]ioint of the frontal l)one. This 

 distance gives a fair indication of the length of the facial parts of the skull. The distance 

 from the front of the premaxillai'y bones would possibly have been a better criterion, l)nt 

 the selection of the above measurement was largely determined by the al)sence of the 

 ])remaxilla' in some of the skulls. The distance EE is the maxiunim width of the skull 

 in the region of the postorbital arch. This gives a fair indication of the breadth of the 

 skull as a whole. The ratio EE (or MM) to MN gives roughly the breadth of the skull 

 in terms of the length of the facial parts. Thus, in skull C the ratio EE (or MM) to MN 

 is ]'.)S-0 : 100, in skull B it is 17;!-:'> : KM); so that C is a relatively broader skull than B. 



The fifteen Okapi skulls specially studied are for convenience di>noted by the letters 

 A — P. The particulars of these, so far as concerns the illustrations ])ulilislied in this 

 Atlas, are as follows : — 



Pr,ATE 13. 



Skull A.— In the British Museum; Reg. No., 1.8.9.51; presented by Sir Harry 

 Johnston in 1901. Sex doubtful: when first described supposed to be female because 

 of absence of ossicones, soft rudiments of which were, however, present ; young, about two 

 thirds groAvn. Localitj- : Semliki Forest, near Lake Albert Edward. The skull is 

 figured by E. Ray Lankester, 'Trans. Zool. Soc.,' 1902, vol. xvi, plates xxxi and xxxii, 

 and ])p. 281 and 290. Figured also in Plates 3 and 8 of this Atlas. This skull, with 

 the corresponding skin (see Plate 44, fig. 1), is the type of Ohaphi rril-i^sniii, Lankester 

 ('Ann. Mag. Nat. Hist.,' ser. 7, x, 59, November, 1902, p. 417). 



Skull B. — In the British ^Muscnim ; Reg. No., (1. 12. 27.1 ; part of a com|ilete skeleton 



