198 SINCLAIR— SKELETON OF LEPTAUCHENIA. [April 22, 



of water as suggested by Cope for Cyclopidius- is not altogether 

 substantiated by the feet, the slender toes of which terminate in 

 small hoof-like elements well adapted apparently, so far as their 

 structure is concerned, to running on firm ground. The slight 

 development of lower incisors and canines indicates, perhaps, that 

 Lcptauchcnia was not a grazing animal, for in modern grass feeders, 

 while the upper incisors and canines may be absent, the lower teeth 

 are broad and flat, well adapted to cropping grasses, while in Lep- 

 taiichcnia they are almost cylindrical. A study of the conditions of 

 sedimentation involved in the accumulation of the so-called clays in 

 which the remains of Leptanchenia occur will, it is believed, afiford 

 a safer clue to its habits than does the anatomy. 



As it has not been possible to have detailed drawings prepared 

 it has seemed advisable to omit full description and present merely 

 some notes on the general structure of the skeleton. 



Skull. — The prominent orbits, the large facial vacuities extend- 

 ing backward between the eyes, the high and almost straight sagitta'. 

 crest, the elongated auditory meatus with thickened lip, the heavy 

 arches and the deep mandible are at once apparent from the figure. 

 Coupled with these as generic characters are the enormously ex- 

 panded auditory bullae and the reduced condition of the anterior 

 dentition. Some differences in proportion appear between this and 

 a previously published figure of the skull of Leptanchenia,^ due 

 probably to the fact that the latter is a composite. 



Vertebral Column. — The dorso-lumbar vertebral formula is 

 twenty, of which fourteen are dorsals. Six vertebrae are coossified 

 in the sacrum, three of them being in contact with the ilium. As 

 shown in the restoration, the anterior dorsals have high narrow 

 spines, sloping backward. These decrease in elevation posteriorly 

 and probably about the twelfth or thirteenth dorsal begin to assume 

 the shape of the wide, transversely flattened lumbar spines. A 

 few proximal caudals are preserved, too few to determine with 

 certainty whether the tail was long or short, but suggesting the 



" Cope, E. D., " Synopsis of the Species of Oreodontidse," Proc. Am. 

 Phil. See, Vol. XXL, p. 547. 



* Scott, W. B., " Beitrage zur Kentniss der Oreodontidas," Morphologi- 

 schcs Jahrhnch, Bd. XVL, Taf. XV., Fig. 15. 



