DE. E. EAY LANKESTEE ON OKAPIA. 285 



canines in the upper jaw, the presence of brachydont selenodont molars, the group 

 of eight anterior teeth in the lower jaw (incisors and canines), and the long diastema 

 between these and the molars — are characters only found in the Pecora and in 

 typical GirafRdtE {VelleriGornia), Cervidse [Cervicornia), or Bovidas (Cavicornia). The 

 absence of " pettitoes " renders Cervine and Bovine aiBnities improbable, whilst 

 Antelopine and Giraffine are more likely. Antelopes without rudimentary digits are 

 known, but are exceptional. The absence of horns would tell no more against Antelopine 

 than Gii'affine affinities, since hornless females are known among the former. 



The great length of the postorbital region of the Okapi's skull (text-fig. 2, p. 284) 

 is, however, not at all Antelopine, and is more nearly approached (though not nearly 

 equalled) by the Giraffe. Moreover, the skull of the Okapi is not only astonishingly 

 long in the postorbital region (see Plates XXXI. & XXXII. ), but it presents a great 

 peculiarity in the fact that this region is in the same horizontal plane as the prseorbital 

 region. In fact, the basicranial axis and the basifacial axis of the Okapi's skull appear 



Text-fig. 4. 



pji. 



Lateral view of the skull of Helladotherium, from the Miocene of Pikermi ; after Gaudry. 



occ, occipital crest ; pji., palatine horizontal ; m.p.h., median parietal boss or tumescence, similar in character 



to, but differing in position from, the lateral bosses of Giraffe or of Okapi or the median boss of Giraffe. 



to lie nearly (not quite) in one plane. This is a primitive and an unusual character. 

 It is more or less retained by the genus Alces (text-fig. 6, p. 286) and others of the 

 Cervidse, where the planes of the two axes form a very open angle ; but in tlie Bovidte 

 a much less obtuse angle is formed by the plane of the basicranial axis where it meets 

 that of the basifacial axis (text-fig. 8, p. 287). 



The whole of the brain-case or postorbital region of the skull of the Bovidse appears 

 to be bent down as on a joint formed across the junction of the cranial and facial portions 

 of the skull (see text-figs. 7 and 8, p. 287). This bending down or angulation of the 

 brain-case has occurred to some extent in Giraffa, as shown in the section (text-fig. 5, 

 p. 286), but much less than in the Bovidse. Although our specimens of Okapi's skull 

 have the basis cranii broken away, we can yet conclude confidently from the relations 

 of the roof and sides of the cranium that there was a complete absence of any such 

 bending or of any angle at the junction of the basicranial axis with the basifacial axis. 



