138. University of California Publications in Geology [Vol.10 



Pleistocene genera by Reinhardt 3 in 1878. The relationship of this 

 genus to the Miocene ground-sloths of Patagonia has been discussed 

 by Scott 4 and Ameghino. 5 



It is of considerable interest to note that Nothrotherium has only 

 recently been definitely recognized, although tentatively recorded by 

 Sinclair in 1905, as a member of the North American Pleistocene 

 fauna. Its distribution over the northern continent, as indicated by 

 the known occurrences in Pleistocene deposits of California and 

 Texas. 7 is apparently much more restricted than that of Megalonyx 

 and Mylodon. It seems not improbable that the genus, when known 

 more completely, will be recognized in other Pleistocene faunas. 

 Among the Rancho La Brea edentates, the nothrotheres rank next to 

 the mylodont sloths in abundance, but are present in far smaller num- 

 bers than the latter. Curiously enough, Nothrotherium is represented 

 in the asphalt by a greater number of individuals than Megalonyx. 



The Museum of History, Science and Art of Los Angeles contains 

 in its Rancho La Brea collection eight more or less complete crania 

 with fragments of perhaps four other individuals. A number of 

 mandibles are also available. All of the better preserved skulls are 

 much larger than Reinhardt 's specimen and belong to adult or nearly 

 adult individuals. Associated with the skulls is one nearly complete 

 skeleton and many separate parts of skeletons. In the present pre- 

 liminary discussion only the skull of the nothrotheres is considered. It 

 is planned to give a fuller account of Nothrotherium from the asphalt 

 beds in which all the material of the genus will be reviewed. 



The present report is based entirely on material contained in the 



a Beinhardt, .1., Kaempedovendyr-Slaegten Coelodon, Vidensk. Selsk. Skr., 

 5 Raekke, naturvidenskabelig og mathematisk Afhandl., vol. 12, 3, pp. 253-349, 

 5 pis., Copenhagen, 1878. 



4 Seott, W. B., Kept. Prin. Univ. Exp. Patag., 1896-1899, vol. 5, Gravigrada, 

 1903-1904. 



•"> Ameghino, F., Notas sobre una pequefia colece.ion de huesos de mamiferos 

 procedentes de las grutas ealeareas de Iporanga en el Estado de Sao Paulo- 

 Brazil, Revista do Museu Paulista, vol. 7, pp. 74-119, 1907. 



11 Sinclair. W. J., New mammalia from the quaternarv eaves of California, 

 Univ. Calif. Publ. Bull. Dept. Geo]., vol. 4, pp. 153-155, pi. 23, figs. l-5a and 8, 

 1 905. 



' In a discussion of the quicksilver deposits of the Terlingua district, Brewster 

 County, Texas. H. W. Turner makes mention (Economic Geology, vol. 1, p. 275, 

 1906) of the finding of ground-sloth remains in a fissure deposit. This material 

 was submitted to Professor J. C. Merriam, who identified several teeth as 

 belonging to Nothrotherium. The specimens were placed in the Museum of the 

 California Academv of Sciences in San Francisco, where they were destroyed 

 by the fire of April 18, 1906. 



'Recently O. P. Hay has described (Proc. U. S. Nat. Mus., vol. 51, pp. 116-123, 

 pis. 6 and 7, 1916) a new species, Nothrotherium texanum, from the Pleistocene 

 of Texas. 



