218 



SOME CHINESE VERTEBRATES. 



symmetry. It consists of an anterior transverse enamel space, succeeded by 

 two small closed triangles, the outer slightly in advance of the inner and more 

 sharply angular. Then follows a terminal Y-shaped space whose outer anterior 



lobe is slightly the longer. The tooth has thus 

 three external and three internal salient angles. 

 No variation from the condition here described is 

 shown by any of the six specimens. 



In the first lower molar of the type there are 

 four salient angles on either side. The posterior 

 enamel space is the usual transverse crescent, an- 

 terior to which are two inner and two outer alter- 

 nating closed triangles. The anteriormost closed 

 space has a small angle on either side at its poste- 

 rior end. The second lower molar has but two 

 closed triangles and at each end of the tooth a 

 transverse closed space, the anterior of which is 

 deeply cut by the first outer reentrant. The third 

 lower molar has the usual three transverse loops, 

 the anteriormost smallest and almost oval in out- 

 line. Like the preceding tooth, it has three ex- 

 ternal and three internal salient angles, but the outer reentrants are very much 

 shallower than the inner. 



In Nos. 7189 and 7192, the antero-internal notch of the first enamel loop 

 of the first lower molar is so well developed that it nearly cuts off a fifth triangle 

 while in No. 7191 this reentrant is still deeper and completely cuts off this triangle 

 so as to produce two external and three internal closed triangles in addition to 

 the anterior loop and the posterior transverse crescent. In this specimen, there- 

 fore, there are four external and five internal salient angles. In No. 7194 this 

 tooth is as in the type. 



Measurements: The following measurements were taken in the flesh by 

 the collector: 



Craseomys aguilus. Type No. 

 7189. E, Enamel pattern of left 

 upper molars. F, Enamel pattern 

 of right lower molars. 



Average 



151 



55 



18 



