38 Dr. J. E. Gray on the Species of Hyrax. 
specimens of H. stnaiticus 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. ruficeps 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#. 
capensis, small and pentagonal in H. syriacus, large and nearly 
tetragonal in H. ruficeps, and large and semiorbicular in H. 
habessinicus. , 
M. de Blainville, in the ‘ Ostéographie,’ ‘‘ Onguligrades,”’ 
figures the hinder part of the skull of three species to show the 
interparietal bone ; he figures it as elongate and subtriangular 
in H. syriacus, large, broad, and roundish four-sided in H. 
capensis, 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 br. 
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. habes- 
sinicus. He seems to have confounded two species under the 
latter name, for fig. 14 is evidently a 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 interparietal is variable in shape 
in Cavia aguti (Wiirzb, naturw. Jahresb. 1860, xvi. p. 158, 
t, 2). 
There is considerable difference in the form of the blade- 
bone in the genera Hyrax and Dendrohyrax. In Hyraz: 
(Nos. 7246, 7249, & 7244) 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 6) the bladebone is broad, 
iuregular, 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 Hyraz 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. “awe t.3.f.1; Blainville, 
