FAUNA OF THE GOSAU FOIIMATION. 



641 



which is flattened, is nearly at right angles to the internal and ex- 

 ternal surfaces, and altogether unlike the narrow rounded base 

 which characterizes the species previously described. This, with 

 the less extension of the alveolar margin forward and greater 

 thickening of the extremity of the jaw to form the parrot-like ter- 

 minal surface, constitute specific distinctions. 



Teeth. 



The teeth have very much the aspect of having been eaten 

 (PI. XXVII. rigs. 11-16), or at least exposed to some solvent which 

 may have slightly dissolved their surfaces ; but the contours are 

 sharp and well preserved ; and though the fangs are in some cases 

 broken, the teeth do not exhibit the indications of ordinary wear. 

 It is very difficult, since they only number nine, to judge whether 

 the differences which are to be detected result from relative position 

 in the jaw, or whether one modification at least is not, as I am 

 inclined to believe, of specific importance. 



These teeth have a triangular crown and a compressed fang. 

 There is a cingulum at the base on the outer side only ; but it 

 merely serves to give a compressed aspect to the base of the 

 crown and to thicken the top of the fang. Even these teeth 

 exhibit certain modifications. First, there is one with the fang 

 perfect ; and this shows that it is closed ; and on the inner side at 

 the base it curves a little and shows an impressed area, as though 

 a successional germ had rested there ; the fang in its upper part is 

 slightly concave from side to side. The tooth is bevelled off obliquely 

 on each side by the cutting-edge of the crown (PI. XXYII. fig. 13). 

 The other side has a transverse cinguloid ridge, considerably lower 

 in position than the bevellings (fig. 14). It extends up towards 

 the bevelled corners at the sides. The crown is convex from side to 

 side ; but the median longitudinal ridge is not distinctly defined. 

 Below the cinguloid ridge the tooth contracts from side to side. 

 The extreme length of the tooth is over 9 millimetres, the extreme 

 width of crown is about 5| millimetres, and its length down to the 

 base 5 millimetres. The width of the fang becomes reduced to 

 between 3 and 4 millimetres. In a second specimen the crown 

 presents the same characters, only that it is flatter on the cinguloid 

 side. A third specimen has the bevellings on the attached side of 

 larger extent, so as to reach further down the tooth ; but all have 

 the crown perfectly smooth, without the slightest trace of serrations 

 on either side. It is quite possible that the bevellings may be 

 produced by wear, though there is nothing to indicate such an ex- 

 planation. 



Then there are two teeth very similar in character, only rather 

 broader in the crown, being fully 8 millimetres wide. These spe- 

 cimens want the bevellings, but have the inner side of the tooth 

 marked, with a narrow middle surface which may be flat or con- 

 cave, external to which the tooth is bevelled vertically on one side 

 and has a thickening at the base of the crown on the other. The 



Q. J. G. S. No. 148. 2tr 



