450 ANATOMY OF VERTEBRATES. 



applied to the base of the paroccipital. The orbits are very 

 obscurely marked off from the temporal fossie : there is no 

 postorbital process. The lacrymal canal commences by two 

 apertures defended by a rough protuberance of the lacrymal 

 bone. There is a well-developed pit for the origin of the in- 

 ferior oblique. The premaxillaries are small and do not join 

 the nasals. The air-sinuses extend from the frontals to the 

 superoccipital ridge. 



In the Indian Rhinoceros {Rhinoceros Indicus, fig. 302), the 

 bones, 3, 7, ii, 15, forming the expanded neural spines of the 

 302 cranial vertebrae, are so 



curved, that the summit of 

 the superoccipital, 3, and 

 the centre of the nasals, 15, 

 form the two pillars from 

 which are suspended the 

 parietals, 7, and frontals, ii, 

 forming an inverted arch. 

 The highest part of the 

 nasals shows the rough flat- 

 tened surface for the attach- 

 ment of the horn : from 



Skull of Iiidiau Rhiuoceros. i • i . , i 



wnicn part tney curve 

 downward, ending pointedly. The premaxillaries, 22, are small, 

 support a pair of incisors, articulate with each other and the 

 maxillaries, and terminate remotely from the nasals. In the 

 African two-horned Rhinoceroses, the premaxillaries are almost 

 obsolete, and usually edentulous in the adult. 



In certain extinct Rhinoceroses the septum narium was partially 

 {Rh, leptorliinus) ^ or wholly {Rh. tichorrhinus) ossified. The arti- 

 culation between the basi- and pre-sphenoids long remains. There 

 is no interparietal. The entopterygoid swells into a tuberosity, 

 and overlaps the palato-pterygoid suture. 



In the Hyrax the elements of the occipital bone are late in 

 coalescing. I have seen an interparietal wedged into the back 

 part of the sagittal suture, and also the upper half of the super- 

 occipital detached from the rest. The ascending process of 

 the malar articulates with the postorbital i3rocess which is 

 formed by both the parietal and frontal bones. The tympanic, 

 which forms the bulla ossea at the basis cranii, has not coalesced 

 with the petrosal. The hinder halves of the palatines enter into 



' xviir. p. 356, figs, 131, 138. 



