1913] Stock: Nothr other iicm and Megalonyx 343 



cave, differing from C. maquinense by the absence of a furrow 

 from the posterior face of the last superior tooth. The genus 

 received its present name from Lydekker 3 in 1880. Nothrother- 

 ium(f) shastense was described by Sinclair 4 from Potter Creek 

 Cave, Shasta County, California, in 1905, the type specimen 

 being a portion of the right ramus of the mandible without 

 teeth. Fourteen molariform teeth were also referred to this 

 species by Sinclair. 



Diagnostic Characters of Species. — Skull slender; larger than 

 in Nothr otherium escrivanense, and cranial portion more ele- 

 vated; point of greatest elevation on frontals; superior border of 

 zygomatic arch distinctly convex; median wall of tympanic bulla 

 pierced by a large aperture ; post-palatine notch acute ; post- 

 palatine foramina large ; inner face of last superior tooth wider, 

 outer face more rounding and narrower than in N. shastense. 



Skull. — The skull from the asphalt beds is fairly well pre- 

 served and the sutures clearly defined. No teeth were associated 

 with this specimen. A tooth found separate from the skull 

 corresponds in section to the second alveolus of the right side. 

 The skull is elongate and more nearly cylindrical than in the 

 genus Megalonyx. The muzzle tapers gradually forward from 

 the frontals. The greatest width of the skull occurs at the pos- 

 terior end of the zygoma. The tympanic bulla is prominent. 

 The transverse crest of the occiput divides this region into two 

 subequal areas. 



The nasals (fig. 1) are long. Close to the median line each 

 nasal pushes a small wedge-like projection sharply into the 

 frontal. The dorsal surface of the nasals is convex in their 

 anterior half, becoming flattened posteriorly. The anterior 

 margin has been broken away. 



In NotJirotherium graciliceps the point of greatest elevation 

 is reached at the junction of the middle and posterior thirds of 

 the frontal (fig. 3), while in N. escrivanense the highest point is 

 on the parietal. The frontals are widest across the anterior half. 



a Lydekker, R., Nicholson and Lydekker, Manual of Palaeontology, 

 ed. 3, vol. 2, p. 1299, 1889. 



4 Sinclair, W. J., New Mammalia from the Quaternary Caves of Cali- 

 fornia, Univ. Calif. Publ. Bull. Dept. Geo)., vol. 4, pp. 153-155, pi. 23, figs. 

 l-5a and 8, 1905. 



