A NEW FOSSIL RUMINANT GENUS. 



15 



at the muzzle and vertex, as it throws a doubt upon some very interesting 

 points of structure in the Sivatherium : 1st, the presence or absence of 

 incisive and canine teeth in the upper jaw, and their number and character 

 if present ; 2d, the number and extent of the bones which enter into the 

 basis of the external nostrils ; and 3d, the presence or absence of two horns 

 on the vertex, besides the two intra-orbital ones. 



Regarding the first point, we have nothing sufficient to guide us with 

 certainty to a conclusion, as there are ruminants both with and without 

 incisives and canines in the upper jaw; and the Sivatherium differs most 

 materially in structure from both sections. But there are two conditions 

 of analogy which render it probable that there were no incisives. In all 

 ruminants which have the molars in a contiguous and normal series, and 

 which have horns on the brow, there are no incisive teeth. In the Camel 

 and its congeners, where the anterior molars is unsymmetrical and separat- 

 ed from the rest of the series by an interval, incisives are present in the 

 upper jaw. The Sivatherium had horns, and its molars were in a conti- 

 guous series : it is therefore probable that it had no incisives. Regarding 

 the canines there is no clue to a conjecture, as there are species in the same 

 genus of ruminants both with and without them. 2. The extent and 

 connections of the incisive bones are points of great interest, from the kind 

 of developement which they imply in the soft parts appended to them. 



In most of the horned ruminantia, the incisives run up by a narrow 

 apophysis along the anterior margins of the maxillary bones, and join on 

 to a portion of the sides of the nasals ; so that the bony basis of the exter- 

 nal nostrils is formed of but two pairs of bones, the nasals and the incisives. 

 In the Camel, the apophyses of the incisives terminate upon the maxilla- 

 ries without reaching the nasals, and there are three pairs of bones to the 

 external nostrils, the nasals, maxillaries and incisives. But neither in 

 the horned ruminants, nor in the Camel and its congeners, do the bones of 

 the nose rise out of the plane of the brow with any remarkable degree of 

 saliency, nor are their lower margins free to any great extent towards the 



