1907.] 



MONKEYS FROM THE AMAZOXIAX REGIOX. 



91 



Legs. Outer side of the same colour as the posterior part of 

 the back. 



Yentral aspect. — General colour a deep dark chestnut reddish- 

 brown, considerably darker than in the Purus species, 21. griseo- 

 vertex. 



Tail very long, dark blackish brown, turning Ijlacker toward 

 the end. 



Text-fig. 21. 



Bact view of head of Midas rufiventer. 



So far as I know the only figure as yet published of a specimen 

 of Marmoset Monkey, closely resembling this type-specimen of 

 Midas riifiventer in the British Museum, is that in the supple- 

 mentary plate 36 of the work of Reichenbach, under the name 

 of " Midas eryihrog aster batterer, Mus. Vindob.," made, as stated 

 on p. 14, from an original sketch by a Mr. T. E. Zimmermann 

 of a skin collected by batterer and preserved in the Vienna 

 Museum. With no little surprise I discover, however, that 

 Pelzeln, the excellent monographer of the Brazilian mammals 

 collected by Natterer, enumerates this very specimen, and also 

 the figure in Reichenbach, as synonyms under the head of Midas 

 lahiatus Geoifroy, a procedure which seems to me more than 

 doubtful, not to say flatly erroneous. In this figure, though 

 worthy of criticism in some respects (the most salient defect 

 being the substitution of the delicate mottling by rough, daubs of 

 black on a greyish ground), one essential feature nevertheless 

 stands out clearly, namely the rust-coloured frontal spot, coinciding 

 perfectly with the abdominal colour. 



I have never been able to consult either the full description, 

 or any figure, or any other useful information concerning the 

 M. elegantidus Slack, Proc. Academy of Natural Sciences of 

 Philadelphia, 1861, p. 463, always C[uoted as a synonym of 

 M. nifiventer Gray. 



