Vol. 4] Sinclair. — Mammalia from Quaternary Caves. 



153 



Cannon-bone No. 43 12 



Width at proximal end 36 mm 



Width at middle of shaft 29 



Greatest thickness at middle of shaft 13.5 



Width across condyles 



Width at nutrient foramen 



Greatest thickness at nutrient foramen. . . . 



No. 4382 



42.5 

 35.5 

 15 



. . . . mm 



1. montanus 

 35 mm 



32 

 14 



25 

 13 



39.5 



NOT11ROTIIERIUM ( ?) SHASTENSE, 11. Sp. 

 PI. 23, Figs. l-5« and 8. 



Type. — No. 8422, Univ. of Gal. Palae. Coll. An incomplete right 



mandibular ramus without teeth. 

 Locality. — Potter Creek Cave, Shasta Co., California. 



This ground-sloth is represented in the cave collection by a 

 large number of specimens. While teeth are wanting in the type, 

 the peculiar shape and dimensions of the alveoli agree so closely 

 with a number of molars from the same cave that there can be 

 little doubt that they should be referred to the same species. 



The type specimen lacks the greater part of the coronoid and 

 angle. The anterior part of the symphysis is wanting, and the 

 alveolar border is somewhat broken. The inferior border (PL 

 23, fig. 2) is strongly convex with the major convexity below 

 the third lower molar. From this point it rises toward the 

 symphysis, which is finite oblique instead of being almost ver- 

 tical as in Megalonyx jeffersonii. The alveolar border in front 

 of the second molar is somewhat broken and there is no trace 

 of an alveolus for the first molar. The anterior opening of the 

 alveolar canal is visible at the anterior extremity of the ramus. 

 Its posterior opening is at the base of the coronoid process, on 

 the outer side of the jaw. 



The molar alveoli extend to the lower border of the ramus, 

 from which they are separated by a thin shell of bone. All 

 have parallel vertical walls, indicating that the specimen is of an 

 adult individual. 



In the second lower molar alveolus (PI. 23, fig. 1) the 

 lateral walls are inclined toward each other and if produced 

 would meet anteriorly. The tooth occupying this alveolus was 

 grooved on both lateral faces, dividing the column into two 

 lobes of which the anterior was the smaller. Each lobe cor- 



