58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



BRADYPUS IGNAVUS Goldman 

 Panama Three-toed Sloth 

 [Plate 22, figs. I, 10] 

 Bradypus ignavus Goldman, Smiths. Misc. Coll., Vol. 60, No. 22, pp. 1-2, 

 February 28, 1913. Type from Marraganti (about 2 miles above Real de 

 Santa Maria), near the head of tide-water on the Rio Tuyra, eastern 

 Panama. 



The three-toed sloth of eastern Panama, apparently a distinct 

 species, is somewhat similar to B. griseus griseus of western Panama 

 in color, but the upperparts are more distinctly spotted with white 

 and the frontal ruff is grayish brown instead of black. The skulls 

 of B. griseus castaneiceps of Nicaragua and B. g. griseus seem in- 

 distinguishable while that of B. ignavus differs from both in appar- 

 ently important details, the nasals being shorter, with the anterior 

 border concave or emarginate, the emargination deepest at the 

 median suture ; the squamosal arm of the zygoma is broader, more 

 rounded, less acutely pointed anteriorly ; the palate is less deeply 

 grooved posteriorly; and the mandible is less produced anteriorly 

 beyond the plane of the first molars. 



In color pattern as well as cranial details B. ignavus differs 

 markedly from B. g. griseus and B. g. castaneiceps and is more like 

 some of the South American species. It appears to be unlike those 

 described, but its exact relationship to some of the South American 

 members of this unrevised group cannot be determined at present, 

 owing to lack of knowledge of their real characters. While the wide 

 range of variation seen in a series of specimens from a given locality 

 would include many of the characters used as specific by Gray in his 

 diagnoses of various species (1871a, pp. 428-449), this variation 

 is shown by examination of Middle American forms to be within 

 definite limits, and when ample material is available the distinctive 

 characters of the species will become better known. 



The type specimen was found one day in the extreme top of a very 

 tall tree where it was resting, its body doubled and limbs folded in 

 such a manner that it might easily be mistaken for the nest of a 

 squirrel or some large bird. 



Specimens recorded by Anthony (1916, p. 364) from Cituro, Real 

 de Santa Maria and Tapalisa in the region of the type locality are 

 darker, more chocolate brownish in general color, and the light dorsal 

 spots are yellowish instead of nearly pure white as in the type. 



Specimens examined: Cituro, 1 *; Marraganti, 1 (type) 2 ; Real de 

 Santa Maria, 3 1 ; Tapalisa, I. 1 



1 Collection Amer. Mus. Nat. Hist. 



3 Two specimens in the U. S. National Museum, from the Atrato River, 

 Colombia, are referable to the same species. 



