40 GEOLOGICAL SURVEY OF TEXAS. 



The first (posterior) premolar presents a crOM^n constructed — first, of a 

 posterior column with a crescentic section, the convexity forward; sec- 

 ond, of a column with crescentic section, with the convexity backwards 

 and outwards; and third, of a cusp which is compressed so as to be an- 

 teroposterior. These cusps are deeply separated on the inner side of the 

 crown, but fused on the external side. In the true molars the tritocone 

 and tetartocone are separated at the postero-external angle of the crown 

 by a deep notch. The stylets diminish in size from the first to the third 

 molar, and there is none between the second and tliird columns of the 

 third molar. On the external side of the protocone in tlie true molars is 

 a deep vertical groove, which is bounded in front by a fold. No cingula. 

 Internal faces of columns gently convex in transverse section. 



Measurements . 



Mm. 



Length of superior true molar series 30 



Diameters of base of M. i 



anteroposterior 10 



transverse 10 



1 

 1 



Diameters of P. m. i J anteroposterior 6 



^ transverse 6 



Length of series of inferior true molars 30 



Diameters of M. iii j anteroposterior 11 



transverse 11 



Diameters M. ii . . 

 Diameters M. iii. 



anteroposterior 9.5 



transverse 5.8 



anteroposterior 13 



transverse 5.8 



There remains a doubt as to whetlier this specimen belongs to the B. 

 gemmifer. The last inferior molar agrees closely with the one referred to 

 that species by me in the Vertebrate Paleontology of New Mexico, in 

 Volume V of the Report of the United States Geological and Geographic 

 Survey West of the 100th Meridian; but this is a slender basis of identi- 

 fication. The typical specimens, which are from the Loup Fork beds of 

 Colorado, I can not at the present find, but hope to do so before my final 

 report to the Geological Survey of Texas is published. 



APPENDIX TO THE REPORT ON THE LOUP FORK TERRANE, 



A small collection made by Mr. Cummins near Goodnight' s, on the 

 Staked Plain, presents characters which distinguish it from the faunae of 

 the Loup Fork and Blanco formations. According to Mr. Cummins, the 

 Loup Fork formation is overlaid by a bed of gravel, which passes under 

 the fossiliferous formation at Goodnight. He consequently regards the 

 latter as of later age than the Loup Fork, while he thinks it older than 

 the Equus beds of Rock creek. The paleontology sustains this view. 



