112 



PROF. E. RAY LAJv'KESTER ON THE 



Feb. 5, 



Text-fig. 35. 

 fr 



occ. 



Drawing, of the natural size, of a young foetal skull of a Giraffe, preserved in 

 the British Museum. The foetus is at so early a stage that no trace of the 

 future horn or ossicone is presented, and moreover the arietal bone does not 

 form the vertex of the brain-case as in the skull drawn in text-fig. 24, p. 101. It is 

 worthy of remark that a line drawn from the occ.-par. iuture to the fronto-par. 

 suture is in this early foetal skull almost at right angles to a line drawn from 

 the latter to the naso-frontal suture, a condition which is even more strikingly 

 exhibited in the adult skull of the Common Ox {Bos) as contrasted with that of 

 Ovis, Ovibos, and Antilopidse. In adult Giraffe the surfaces of the frontal and 

 parietal are more nearly parallel, and in Okapia quite so. It is a very cui-ious 

 fact that in Sos the whole posterior region of the brain-case formed by the 

 parietals, which in Okapia stretches horizontally backwards from the fronto- 

 parietal suture to a distance as great as that occupied by the frontal portion, is 

 abolished ! The parietals are vertical and not horizontal, and a sort of false 

 occipital ridge is formed by the fronto-pai'ietal suture. The very j'oung Giraffe- 

 foetus approaches this condition. 



In answer to this question, it appears to me that the following 

 statements are justified : — 



1 . Since the bony horn-core of Bovidse originates as a part of 



the osteogenetic tissue of the frontal bone, it cannot 

 (according to our present knowledge) be identified without 

 considerable qualification with the free tegumentary 

 tossicones of Giraffidfe. 



2. The upgrowth (tumescence) of the frontal bone in Okapi and 



of the parietal and frontal in Gii-afie, which foi'ms the 

 bulk of the lateral hoi-ns in those animals, is more nearly 

 similar in nature to the bony horn-cores of Bovid?e than 

 are the ossicones of Giraffidte. 



3. The frontal tumescence or upgrowth of Okapi cannot be 



considered as morphologically identical with the 2^((''>'i6tal 

 tumescence or upgrowth of Giraffa. 



4. The free lateral ossicone of Girafci might legitimately be con- 



sidered as morphologically identical with the free lateral 

 ossicone of Okapi. The free tegumentary ossicone of an 



