150 Bulletin American Museum of Natural History. [Vol. XXXIV, 
Acknowledgments. 
The material studied in the present connection numbers not far from 
1020 specimens, of which about 610 are in the American Museum, about 150 
in the British Museum, 112 in the United States National Museum (includ- 
ing the collections of the Biological Survey), 42 in the Field Museum of 
Natural History*of Chicago, 53 in the Cambridge Museum of Comparative 
Zoology, 24 in the Carnegie Museum of Pittsburgh, and 17 in the museum 
of the Academy of Natural Sciences of Philadelphia. To the authorities 
of these several institutions I am indebted for prompt and most cordial 
responses to my requests for assistance, they having freely loaned types as 
well as other material. Especially and most emphatically am I indebted to 
Oldfield Thomas, of the British Museum, for not only free access to the 
material in his charge, but for information, given verbally and through 
correspondence; to Gerrit S. Miller, Jr., of the U. S. National Museum, 
E. W. Nelson and E. A. Goldman, of the Biological Survey, W. H. Osgood 
of the Field Museum, Mr. Samuel Henshaw and Dr. G. M. Allen of the 
Museum of Comparative Zoology, and Dr. Witmer Stone of the Philadelphia 
Academy of Natural Sciences. , 
Mention should also be here made of the field explorers who have made 
accessible for study the large amount of pertinent material in the American 
Museum. First among these is Leo E. Miller, who for the last four years 
has been continuously in the employ of the Museum as a field assistant in 
South America — in western Colombia, Venezuela, British Guiana, and in 
Brazil and Paraguay with the Roosevelt Expedition, who has collected 
more than half of the South American squirrels now in the American Mu- 
seum. William B. Richardson, in Ecuador and extreme southwestern 
Colombia, and G. M. O’Connell in the Bogota district, have also gathered 
a large amount of valuable material. In earlier days important collections 
were made for the Museum in Peru by H. H. Keays, in the Santa Marta 
district of Colombia by H. H. Smith, and in various parts of Venezuela by 
. M. Klages and M. A. Carriker, Jr. Of borrowed material mention may 
be made of the important material collected by E. A. Goldman in Panama 
(Biological Survey collection), by W. H. Osgood in Venezuela and Peru 
(Field Museum), by J. Steinbach in Bolivia (Pittsburgh Museum), by H. H. 
Smith in Matto Grosso (Philadelphia Academy collection); P. O. Simons 
in Ecuador, Peru and Bolivia (British Museum), and by Fraser, Bridges, 
Garlepp, Stolzmann, Palmer, Pratt, Fleming, and others in western South 
America, and Alphonse Robert, McConnell, and others in Guiana and 
eastern Brazil (British Museum). 
