246 



/jti.st upper temporary molar, Fig. 13. — Breadth, 17 lines; width, 10 lines. 



Upper second or third molar, Fig. 14 — Length of crown, 25 lines; breadth, ll lines; 

 width, 13 lines. 



An intermediate lower molar, Fig.15. — Length of crown, 24 lines; breadth, ].'5.', lines; 

 width, 9f lines. 



Upper molar, Fig. 10. — Length of crown, 22 lines ; breadth, 13£ lines ; width, 14£ lines. 



Lower molar, Fig. 17. — Length of crown 22£ lines; breadth, 14| lines; width, 11£ 

 lines. 



Among a small collection of fossils from Texas, submitted to my examina- 

 tion by Professor S. 13, Buckley, there is a specimen of an upper molar tooth 

 of a horse of peculiar character, represented in Fig. 18, Plate XXXIII. 

 The exact locality from whence the specimen was obtained is unknown. 

 The tooth is apparently a fourth or fifth of the series, and is only sufficiently 

 worn to exhibit the course of the enamel layers on the triturating surface. 

 The tooth is longer than in the domestic horse, and is rather narrower than 

 usual in relation with its fore and aft diameter. The folding of the enamel 

 defining the median lakes of the triturating surface is as complex as in Equus 

 complicatus, but in a different position. In the latter the folding is greatest 

 on the contiguous sides of the lakes, as seen in Figs. 11 and 14, but in the 

 tooth under consideration the contiguous sides of the lakes are less folded 

 than usual even in the domestic horse, while the enamel border at the inner 

 sides of the lakes is folded in an unusual degree. Further, the broad inner 

 peninsular fold of the triturating surface, which in the domestic horse and 

 other known species has a simple oval, elliptical, or reniform outline, in this 

 specimen is of extreme width, narrow, and folded at the extremities. The 

 width of this inner fold or column is uniform throughout the length of the 

 crown. 



The length of the crown of this tooth, without the fangs, in the entire con- 

 dition has been upward of 4 inches. . Its fore and aft diameter at the trit- 

 urating surface is 16 lines; its transverse diameter at the middle of the same 

 is 1 inch. 



Fig. 19, Plate XXXIII, represents a fragment of an upper molar sub- 

 mitted to my examination by Professor J. S. Newberry. It was obtained 

 from the lignite-beds of Shoalwater Bay, Washington Territory. It presents 

 nothing which distinguishes it from the corresponding part of the molars 

 of the domestic horse. 



The length of the crown externally is 2f inches, and I he fore and aft 

 diameter of the triturating surface is 14 lines. 



