88 DR. E. A. GOELDI ON MARMOSET [Jan. 15, 



5. On some new and insufficiently known Species of Marmoset 

 Monkeys from the Amazonian Region. By Prof. Dr. 

 Emil a. GtOELDI, C.M.Z.S., Director of the Para Museum. 



[Eeceived November 23, 1906."| 



(Text-figures 20-23.) 



On the occasion of the Sixth International Zoological Congress, 

 held at Berne (Switzerland) in August 1904, I presented a paper, 

 "Nova zoologica from the Amazonian Region, dealing especially 

 with new Vertebrates," in which I discussed at some length new 

 and little-known representatives of the family of Callitrichida? 

 (Hapalidfc, auctorum*) from the Upper Amazon, especially from 

 the Rio Purus, as follows : — (1) A species of Midas whose close 

 relationship with Midas rvfiventer Gray I recognised at first 

 sight, and to which later on, after comparing it with the 

 type-specimen of this latter in the British Museum in London 

 (at the time of my visit to the International Ornithological 

 Congress in July 1905), I decided to give the name of Midas 

 griseovertex. (2) A second species of Midas, evidently related to 

 M. labiatus Geoflr. (1812), M. illigeri (id. 1845), and M. weddeUii 

 (id. 1849), and having as its most characteristic distinguishing 

 feature an enormously long white moustache, which afterwards, 

 on the same occasion, I decided to name Midas imj^erator. 

 (3) Midas pileatus, described by Geoffrey in 1848 from the original 

 specimen from the Rio Javary, kept in the Paris Museum, and 

 until recently not represented in any other Museum, so far as 

 could be judged from current zoological literature. I was then 

 able to show a splendid pair of this very rare species. (4) Midas 

 fuscicoUis, described so long ago as 1823 by Spix, but only from 

 immature specimens, the habitat of the adult animal of both sexes 

 having escaped notice, as it appears, in a surprising manner until 

 1904. (5) Midas mystax Spix, originally described from the Rio 

 Solimoes, represented in my exhibited collection by a very dark 

 specimen from the Rio Jurud. 



One of the essential conditions for arriving at certainty in my 

 conclusions, as above suggested, was the careful examination of 

 certain individuals kej)t as type-specimens in the British Museum. 

 The purpose of the present aiiiicle is principally to record the 

 result of my investigation in this respect, which proves to be most 

 interesting and instructive. To say it at once : the most remark- 

 able and unexpected discovery was the fact, that of the two 

 specimens of Midas rufiventer, type and quasi co-type, on the 

 shelves in the British Museum, the latter does not coincide with 

 the former, but, on the contrary, should constitute the type- 

 specimen of a new, overlooked, and undescribed species of the 

 genus Midas. 



* See Thomas, Ann. Mag. N. H. (7) vol. xii. (1903). 



