354 Mr. 0. Thomas — Some Notes 



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

 Amazon, tliere occur a very uniform series of forms which 

 ma}' or may not be divisible into two or more species, but 

 which it is impossible at present to clear up witliout many 

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

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



Throughout this area the sloths are rather larger than 

 B. tridactyhis ; the speculum is of normal size, as in that 

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

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

 and tlie band of yellow velvety hair which 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~ 

 dacti/lus, and has generally a much inflated frontal region. 

 The floor of the mesopterygoid fossa is usually fiat, 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 tiian tlie latter. 



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

 Amazonian and the S.E. Brazilian — not that as yet 1 can see 

 any valid reason for distinguishing the two specifically, but 

 merely to help later workers. 



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

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

 i>ptciili'ger, Fitz. 1871) (Borba, Lower Madeira) ; proble- 

 tnaticus. Gray, 1849 (Para) ; vnicolor, Fitz. 1871 (Para) ; 

 .^mithii, Gray, 1869 (Para), B. viarmoratus, Gray, 1849 

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

 and, if the Upper Amazon infuscatus proves distinguishable, 

 would be the first name for the Lower Amazon form. 



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

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

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

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

 buco — based on Marcgrav). 



Series from many localities are needed before these Bra- 

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

 mens — apart from M.Robert's set from Para already mentioned 

 — consisting of isolated examples, often without any exact 

 locality at ail. 



Bradypus boUvi'ensis, Gvay, 187 1 (type B.M. no. 46.7.28.24), 

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



* Put iu valid form on p. 64 of the article on Bradi/jms. 



