90 SINCLAIR— ADDITIONS TO FAUNA OF LAprii 24, 



Measurements. 



Total length of skull (incisors to condyles) 310 



Length, i-^m^ right 195, left 199 



Length, p^-m^ right 121, left 127 



Length, premolar series right 59V2, left 64 



Length, diastema behind ig right 11, left 9 



Length, diastema behind c 18 



Length, diastema behind p- right 18, left 20 



Length, lower premolar-molar series 106 



Length, lower premolars 3^ 



Depth of jaw in front of p, 32 



Depth of jaw below middle of mj 40 



Length of radius 195 



Width of radial shaft at middle 24 



Drepanomeryx falciformis gen. et sp. nov. 

 Type No. 12072 Princeton University Geological Museum, col- 

 lecting locality lOOoC, a horn of the left side (lacking tip) and the 

 basal portion of the right horn (Figs. 14, 15). 



Frontal not cavernous at base of horns. Horns non-deciduous, 

 rising immediately above upper posterior margin of orbit, sloping 

 backward and upward and at the same time curving inAvard, at 

 base almost circular, but flattening upward in the transverse plane 

 extending backward and inward from the orbits, producing a scimi- 

 tar-like structure which curves inward toward its fellow on the op- 

 posite side. Horns without any suggestion of twist, proximal half 

 comparatively smooth and free from pits and irregularities, such 

 faint groovings as are present being longitudinal. Distally, and es- 

 pecially toward the outer margin, the surface is rough and pitted, 

 but this seems to be due to sand-blasting or water-wear which has 

 destroyed the outer table of bone. A broad groove is visible 

 throughout the central portion of the shaft on the posterior aspect 

 of the horn. Horns solid throughout, the surface, texture resem- 

 bling that of the Pronghorn Antelope. 



No teeth have been found in the Snake Creek beds which can be 

 referred, even provisionally, to the new form, unless those which 

 have been correlated by Matthew and Cook with their Neotra- 

 gocerus improvisus, and the lower jaw described under that genus 

 in the present paper, should be associated with the curved type of 

 horn found in Drepanomeryx rather than with the straight horns of 

 Neotragocerus. 



