MAMMALIA. 1 1 



This is one of the most easily distinguished of the species of this very con- 

 fused genus, which requires a complete revision, but this can only be done with 

 effect by a person living in the country, so that he might observe whether the 

 slight differences of shade in the colours on which the species have been dis- 

 tinguished are permanent during the different ages of the animals of the same 

 troop and forest. Of the Brazilian travellers, Spix appears to have enjoyed 

 the best opportunities for such a revision ; but unfortunately he delayed the com- 

 position of his work until his return to Europe, and instead of unravelling the 

 species, he has even added considerably to their confusion. 



PITHECIA. 



This genus should be restricted, as Spix has done, to the species which are 

 covered with long, dry, crisp, harsh hair, and have a very bushy tail. 



Buffon designated them by the name of Saki, and described two kinds of 

 them, which have been defined by systematic writers as P. leucocephala and 

 P. rufiventer. 



Dr. Kuhl, in his monograph of Monkeys, in his Beytriige, described two 

 other species under the name of P. ochrocephala and P. rufibarbata; but M. Tem- 

 minck, I suspect without sufficient examination, has considered the specimens 

 on which these descriptions were founded, to be only different ages of the two 

 species described by M. Buffon and M. Geoffroy St. Hilaire. 



Spix, in his colossal work on Brazilian Monkeys and Bats, described as new 

 three species under the names of P. hirsuta, P. inusta, and P. capillamentosa : 

 the latter has been considered, and, apparently correctly, to be the same as 

 P. rufiventer of M. Geoffroy and Buffon. 



M. Lesson, who does not appear to have had the opportunity of examining a 

 single specimen of the genus, divides the Pithecice into four sub-genera, each 

 containing a single species ; his two first sub-genera contain the animals under 

 consideration. 



The first of these sub-genera he calls P. nocturna, considering P. rtfiventer 

 of Desmarest as the type of the species, P. leucocephala, Geoffroy, as the first 

 variety, and P. ochrocephala, Kuhl, as the young of this variety. P. rufibarbata, 

 of Kuhl, constitutes his second, and P. monachus, of Geoffroy and Kuhl, his third 

 variety, regarding P. rufiventer, Temminck, as a synonym of P. rufibarbata. 



The second species he calls P. leucocephala, considering the Yarkee, Simia 

 leucocephala, of Audebert and Humboldt, as the type; P. hirsuta, of Spix, as pro- 



