354 



Mr. O. Thomas — Some Notes 



South of Guiana, from Para to Rio, and westwards up the 

 Amazon, tiiere occur a very uniform series of forms wliich 

 may or may not be divisible into two or more species, but 

 which it is impossible at present to clear up without many- 

 more sets of specimens. One locality only — Para — is well 

 represented, as M. Robert got a series tliere in 1904. 



Throughout this area the sloths are ratiier larger than 

 B. tridaclyhis ', the speculutn is of normal size, as in that 

 species, and of a ratlier less dark yellow colour, the general 

 colour is brown mottled to a very variable extent with white, 

 and the band of yellow velvety hair wiiich passes across the 

 forehead is usually about half an inch in breadth — say, 10- 

 15 mm. The skull averages rather larger than that of tri- 

 (lacti/Jus, and has generally a much inflated frontal region. 

 The floor of the mesopterygoid fossa is usually flat, with or 

 without median septum, and without special perforations. 

 The teeth, although variable, are usually of what may be 

 called normal proportions, the pseudo-incisor smaller — gene- 

 rally much smaller — than the molars, and the pseudo-canine 

 decidedly larger than the latter. 



The names for these sloths may be put in two groups — the 

 Amazonian and the S.E. Brazilian — not that as yet lean see 

 any valid reason for distinguishing the two specifically, but 

 merely to help later workers. 



(1) Amazonian: B. infuscahis, Wagl. 1831 (Brazil near 

 Peruvian boundary) ; hrachydactylus, Wagn. 1855 (syn. 

 t^j^tciilige?', Fitz. 1871) (Boiba, Lower Madeira) ; proble- 

 invticus, Gray, 1849 (Para) ; inncolor, Fitz. 1871 (Para) ; 



,i^mithii\ Gray, 1869 (Para). B. warmoratus, Gray, 1849 

 (" Brazil ■'■'), seems also to belong here, judging by the type, 

 and, if the Upper Amazon infuscaius proves distinguishable, 

 would be the tirst name for the Lower Amazon form. 



(2) S.E. Brazilian : B. ai, Wagl. 1831, nee Less. 1827 

 (R. Matheus, Espirito Santo) ; hrasiliensis, Blainv.* 1839 

 (Rio Janeiro) ; palUdiis, Wagn. 1843 (Rio Janeiro) ; hlain- 

 viUei, Gray, 1849 (Brazil) ; dorsalis, Fitz. 1871 (Pernam- 

 buco — based on IMarcgrav). 



Series from many localities are needed before these Bra- 

 zilian sloths can be properly worked out, the available speci- 

 mens — apart from ]\1. Robert's set from Para already mentioned 

 — consisting of isolated examples, often without any exact 

 locality at all. 



Bradypus bolivi'ensts, Gray, 187 1 (type B.M. no. 46.7.28.24), 

 seems to be a valid species. Its speculum is of medium size, 



* Put in valid form on p. 64 of the article on Bradypua. 



