DE. E. EAT LANKESTEE ON" OKAPIA. 



293 



to the supraorbital frontal horns of Cervidse and Bovidge. On the other hand, the 

 I)aired supraorbital frontal tumescence of Okapia (text-fig. 2, p. 284), whilst not identical 

 with the paired tumescence of the parietal in Giraffa, does, it appears to me, corre- 

 spond in position and probably genetically with the supraorbital " ossicusp" developed 

 on the frontal bone of Samotherium and of the Bovidse and Cervidas. 



From this statement, it will be evident that I regard the Giraffidse as presenting a 

 more generalized ancestral condition of the horn-bosses than is found in any other 



Test-iig. 12. 



' otm. 



Lateral view of the skull and lower jaw of a very young Giraffe, measuring 30-8 centimetres from the 

 occiput to the anterior border of the prajmaxilla. This is the same specimen as that represented in 

 fig. 11, and is preserved in the British Museum. The drawing is five-twelfths of the natural size. 



occ, occipital crest ; (jtl., Giraffine conical tumescence of the parietal bone, above which is developed the 

 epiphysis {f.oss.^\ sfp., the fronto-parietal suture; ot.l., position of the lateral tumescence of the Okapi, 

 absent here ; fft.m., position of the median frontal tumescence of the Giraffe, which in this youno' 

 specimen is still entirely undeveloped ; otm., position of the median tumescence of the Okapfs skull 

 (basinasal) ; jplv., prselacrymal vacuity ; can., bifoliate canine ("deciduous dentition). 



group of the Pecora. We have, indeed, in the Giraffidfe, taking into consideration its 

 various extinct members, an unspecialized condition of the tendency to horn-formation. 

 We know in them of either well-grown ossicusps or incipient osseous horn-bosses of 

 six locally different origins, viz. : (1) paired frontal supraorbital growths (Okapia, 

 Samotherium, small pair of Sivatheriwn) ; (2) paired parietal growths [Giraffa, 

 Sivatherium, Bramatherium) ; (.3) paired occipital growths (large hinder pair of 

 Bramatherium, small pair of five-horned Giraffe); (4) median nasal growth (at the base 



