38 Dr. J. E. Gray on the Species o/'Hyrax. 



specimens of H. sinaiticus the yellow streak is deeper and 

 brighter-coloured than in others. It appears more marked in 

 the younger and smaller specimens in the British Museum 

 than in the larger and older ones ; and it is rather indistinct in 

 the two skins which I believe may be H. rujicejys from Abys- 

 sinia. 



Professors Hemprich and Ehrenberg proposed to use the 

 form of the interparietal bone as a distinctive character for the 

 species : thus they described it as large and trigonal in H. 

 capensisj small and pentagonal in H. syriacus, large and nearly 

 tetragonal in H. rujice'ps^ and large and semiorbicular in H. 

 hahessinicus. 



M. de Blainville, in the ' Ostdographie/ " Onguligrades," 

 figures the hinder part of the skull of three species to show the 

 interparietal bone ; lie figures it as elongate and subtriangular 

 in H. syriacus^ large, broad, and roundish four-sided in H. 

 capeiisis, and very broad in H. ruficeps. The part figured as 

 the interparietal in the last species is the broad upper edge of 

 the occipital bone. 



Dr. G. V. Jaeger, who has several skulls from the Cape, 

 collected by Dr. Ludwig, and from North Africa by Dr. 

 Heuglin, has written an essay to show that the interparietal 

 bone of the same species varies much in form and size ; he 

 figures ten varieties of it in H. capensis and three in H. hahes- 

 sinicus. He seems to have confounded two species under the 

 latter name, for fig. 14 is evidently 2<, Dendrohyrax ^ Dr. Jaeger 

 having mistaken the broad upper edge of the occipital bone 

 for an interparietal : he also figures the interparietal of a spe- 

 cies sent from West Africa by Mr. Dieterle, which he names 

 H, sylvestris, which is also a Dendrohyrax ; but the inter- 

 parietal is of a very different shape from those of the two 

 skulls of the West African D. dorsalis in the British Museum. 



Dr. Jaeger shows that the intei-parietal is variable in sha])e 

 in Cavia aguti (Wiirzb. naturw. Jahresb. 1860, xvi. p. 158, 



There is considerable difference in the form of the blade- 

 bone in the genera Hyrax and Dendrohyrax. In Hyrax 

 (Nos. 724^, 724^, & 724 /*) it is elongate, half as long again 

 as broad, with a short, broad process at the lower side of the 

 condyle. In Dendrohyrax (No. 1142 h) the bladebone is broad, 

 irregular, four-fifths as broad as long, with an elongate com- 

 pressed process on the lower side of the condyle ; the lower 

 edge of the bone in Hyrax is sloping for half its length, and 

 then nearly straight ; in Dendrohyrax this edge is arched from 

 the condyle to the end, the broadest part being near the middle 

 of the lower, edge (see Cuvier, Oss. Foss. t. 3. f. 1 ; Blainville, 



