26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



of a ground sloth, and. about 18 inches from it, a fragment of coarse 

 dark pottery. There was no evidence of previous digging that I could 

 discover ; and the bone and pottery had every appearance of having 

 been deposited on the former surface of the cave floor and subse- 

 (juently covered by the gradual accumulation of detritus, (d) Both 

 of these caves are situated on the side of a high ridge where the 

 material composing their floors is entirely removed from the action 

 of streams, (e) In general the ground sloth bones were, associated 

 with the human remains in exactly the same manner as the bones of 

 Isolohodon and Plagiodontia, rodents which are positively known to 

 have been contemporary with man. 



ACRATOCNUS (?) COMES sp. nov. 

 Plate 5, fig. 2; plate 6, fig. 2; plate 8, fig. r ; plate lo, fig. i 



Type. — Right femur (lacking distal extremity) of adult, No. 

 253178, U. S. Nat. Mus. Collected in large cave near St. Michel, 

 Haiti, March, 1925, by Gerrit S. Miller, Jr. 



Characters. — A small ground sloth agreeing in general size with the 

 Porto Rican Acratocnus odonfrigonus Anthon} ; its weight probably 

 not exceeding 50 pounds. Femur resembling that of the Porto Rican 

 sloth, and, like it, with a well developed lesser trochanter and without 

 noticeable antero-posterior compression of the shaft, but modified 

 for more directly perpendicular weight-bearing. 



Femur. — The femur differs from the corresponding bone of Acra- 

 tucnus odontrigoniis in at least two features which are important 

 enough to indicate specific or, possibly, generic distinctness, (i) The 

 intertrochanteric ridge is similar in position and development to the 

 corresponding structure in A. odontrigoniis, but it is supplemented 

 by a large and conspicuous tubercle situated at the middle of the 

 shaft at a level slightly below that of the lesser trochanter. This 

 tubercle, of which no obvious trace exists in the numerous Porto Rican 

 femora with which I have compared the Haitian specimen, forms 

 the culminating point of a general thickening of the bone which 

 imparts to the upper fourth of the shaft, as viewed from the side, a 

 strongly angular-convex profile very diff'erent from the flat or slightly 

 concave profile of the same region in A. odonfrigonus (see pi. 6). 

 (2) The neck is shorter than in Acratocnus odontrigonus and is less 

 bent outward and forward from the axis of the upper half of the 

 shaft; as a result, the head is set so as to diverge less noticeably 

 from the general contour of the shaft. The differences in this respect 

 between the Porto Rican and Haitian animals are of the same kind 



