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PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



[Nov. 21, 



contours are parallel, and not divergent outwards and upwards. 

 There is nothing in the Macrauchenia resembling the deep notch 

 between the supra-occipital and the base of the paramastoid, into 

 which a part of the mastoid fits in Auchenia. In contour, in fact, 

 the occiput of the Macrauchenia resembles that of the Palceotherium 

 more nearly than that of any other Mammal. But, on the whole, I 

 think it must be admitted that the resemblance of the back of the 

 skull of the Macrauchenia to that of Auchenia is sufficiently close 

 to justify the conclusion, that the predominance of the Cameline 

 type, so marked in the neck, was maintained in the head of the 

 extinct Mammifer. 



The fossil which remains for description (Plate YI. fig. 4) consists 

 of two fragments of the matrix (a and h), which fit together, and to 

 which adhere certain portions of the upper jaw and palate, together 

 with the fractured remains of three grinding-teeth and part of the 

 alveolus of a fourth, all of the right side, and in a continuous series. 

 The alveoli and part of the crowns of these teeth are contained in the 

 larger fragment of matrix, — the smaller fragment fitting against the 

 larger and the teeth which it contains, and exhibiting the impressions 

 of the grinding surfaces of three teeth and of their inner faces, a 

 jDortion of dental substance adhering to the latter, in the case of the 

 two anterior teeth. Of the hindermost tooth nothing is left but the 

 impression of one fang. 



The impression of the grinding surface of the first tooth is nearly 

 four-tenths of an inch long, convex from before backwards, concave 

 internally : the outer boundary of the impression is broken away, 

 a fragment of dental substance adhering to the posterior part of its 

 inner face. The part of the larger portion of the matrix (a) which 

 should contain the alveolus of this tooth is absent. The antero- 

 posterior extent of the coronal impression of the second tooth is a 

 little more than 0-4 of an inch ; it is concave from before backwards 

 externally, nearly flat internally, and shelves with a slight convexity 

 upwards and inwards. The inner boundary of the impression is, as in 

 the preceding ease, markedly concave; and a much larger fragment of 

 tooth- substance adheres to it. The outer boundary of the impression 

 is broken away, but much more in front than behind, where its width 

 is fully 0-4 of an inch. The impressed line which separates this im- 

 pression from the next is convex forwards. Corresponding with this 

 impression there are, in the larger fragment of matrix, an almost 

 entire conical posterior fang, about 0*4 of an inch long, lodged in a 

 complete bony alveolus, whose outer wall is broken away, and the 

 posterior half of a similar alveolus for an anterior fang : there is no 

 trace of a third alveolus or fang ; and, indeed, there seems to be no 

 room for one. The fang which exists is connected below with a 

 portion of the crown : but this is so broken, that all that can be 

 remarked of it is its marked internal convexity. 



The coronal impression of the third tooth is half an inch long ; 

 like the preceding, its face shelves upwards and inwards. The poste- 

 rior part of its outer margin is broken away; but it is clear that this 

 crown was quite as wide as that which preceded it, if not wider ; 



