356 Some Notes on Three-toed Sloths. 



Bradypus macrodon, sp. n. 



Most nearly allied to B. infuscntus, but the teeth heavier. 

 General colour pale brown, the white marbling o£ the 

 posterior back generally extensive, with a well-marked brown 

 median line, but in one specimen there is scarcely any white, 

 and in another but little. Face and chin brown, the light 

 frontal band narrow, about half an inch (say, 10-15 mm.) in 

 breadth, whitish rather than yellow in most of the specimens. 

 Hairs on crown overhanging the frontal band rather darker 

 than those on the body generally. Speculum o£ medium 

 size, 2| inches long in the type, paler yellow than in most 

 other species, its median black band broad. Limbs freely 

 marbled with white. 



ISktdl much as in B. in/uscatus, the forehead rather less 

 convex than usual. Nasals, as usual, quite variable in shape 

 and length, some convex and some concave anteriorly. Inter- 

 parietal also extremely variable, its autero-posterior diameter 

 in the type 15 mm., and in another specimen 7 mm. Meso- 

 pterygoid fossa widely open, its floor smooth and flat, or with 

 a slightly raised median ridge, but without deep pits or exca- 

 vations. 



Teeth very large, much heavier than in infuscatus. 

 Pseudo-incisor very large, oval in transverse section, the 

 longest diameter pretty well equalling that of the molars, 

 4*3 mm. in the type, 5 mm. in another specimen. Pseudo- 

 canine similarly very large and heavy, its greatest diameter 

 about 6'2 mm., far exceeding the molars in bulk. Molars 

 rarely less than about 5 mm. in greatest diameter. 



Skull-dimensions of type : — 



Naso-occipital length 78'5 mm. ; condylo-basal length 78"3 ; 

 greatest breadth (on squamosal) 56 ; nasals, length 12-5, 

 least breadth 12*3; interorbital breadth 25*5; palate length 

 from gnathion 29 ; postpalatal length 43 ; tooth-series 29 ; 

 breadth between outer sides of pseudo-canines 22'6. 



Ilab. Sarayacu, Upper Pastasa River, Orienteof Ecuador. 



Type. Adult male. P.M. no. 80. 5. 6. 56 *. Collected by 

 Clarence Puekley. Seven specimens examined. 



This species is no doubt most nearly allied, as is natural, to 

 B. infuscatus, but differs by the materially larger size of the 

 teeth. Even in this character, however, one specimen fails 

 (skull no. 80. 5. 6. 59) ; but among sloths such variations 

 must be expected. 



* The skulls were not individually allocated to the skins when they 

 came, but I think there is little doubt as to the reference to each other 

 of the tjpe-skin and skull. 



