596 DR. J. E. GRAY ON A NEW LEMUR. [May 23, 



It seems therefore, from what has heen above stated, to be mani- 

 fest that the mighty Amazons, tliough it may in some cases, as shown 

 by Mr. Wallace and as noted above, separate allied species, does not 

 constitute the true southern boundary of tlie Guianan avifauna, which 

 is so remarkably distinct from that of the wood-region of South- 

 eastern Brazil, To arrive at this boundary we must proceed further 

 southwards nearly to the banks of the River Parnaiba, where the 

 Amazonian wood-region terminates, and the high open country which 

 forms the campos of Inner Brazil debouches upon the x\tlantic. It 

 is obvious that the wood-inhabiting species which form so large a 

 proportion of the neotropical avifauna could never pass a barrier ot 

 this character, which offers as complete a physical obstacle to their 

 passage as wovild a tract of sea of similar extent. We can therefore 

 fully agree with the conclusions corresponding to those arrived at by- 

 Mr. Bates in his elaborate " INIemoir on the Diurnal Lepidoptera of 

 the Amazon-valley"*, namely : — 



( 1 ) That the Para district belongs to the same zoological province 

 as the Guianas, and has received its bird-population mainly from 

 that quarter. 



(2) That in certain cases (amounting to about 17 per cent, of the 

 whole number of species after excluding those of general distribu- 

 tion) variation has taken place, which has resulted in the production 

 of new specific forms of greater or less degrees of distinctness. 



(3) That in some of these cases the River Amazons has operated 

 as a physical barrier, and has isolated these derivative forms from 

 their Guianan allies, thereby leadhig to an accumulation of varia- 

 tions, which have ultimately resulted in the specific differences now 

 observable. 



2. Note on u New Species or Variety of Lemur in the Society's 

 Gardens. By Dr. J. E. Gray, F.R.S., V.P.Z.S., &c. 



(Plate XXXI.) 



PROSIMIA FLAVIFRGNS, S23. UOV, 



Fur soft, silky, bright pale red brown ; hinder part of the back 

 rather darker. Nose and feet dark red brown, (/ircumference or 

 the face, side of the chin, the throat, and chest pale reddish yellow. 

 Iris of eyes grey. Male. 



Hab. Madagascar; Zoological Society's Gardens, May 15, 1867. 



This is one of the Lemurs which difters from the other described 

 species only in a variation in the shade and disposition of the colours. 

 Whether these are varieties or distinct species must be left to be 

 decided by those who can study them in their native haunts. The 

 one here described is a full-grown male. The end of the tail in the 

 living specimen is imperfect. 



* Trans. Entom. Soc. n. s. vol. t. pp. 223, o35. 



