PREFACE vii 



keeping. In Paris, Monsieur le Docteur E. L. Trouessart, in whose 

 charge is the magnificent collection of Mammals in the National 

 Museum of the Jardin des Plantes, assisted the Author by every means 

 in his power, and placed at his disposal that wonderful collection of the 

 Primates which contains so many of the types of the old Authors, an 

 intimate knowledge of which is necessary for the determination of 

 the species they represent. In the great Museum at Leyden, Holland, 

 so rich in specimens of the Lemuroidea and examples of other Pri- 

 mates from the islands of the Eastern Archipelago, the Director, Dr. 

 F. A. Jentink, and in his absence Administrator Vesteroon Wulver- 

 horst made the Author's labors in the Institution easy and pleasant. 

 In Berlin, Herr Paul Matschie, Curator of Mammalogy, placed the 

 grand collection of Primates so rich in examples of African species 

 especially of Chimpanzees, Gorillas, Guenons, (Lasiopyga) and Colo- 

 bus or Guerezas, at the Author's service, and aided him in every way 

 possible. Also to Herr O. Neumann for information concerning the 

 new species of monkeys obtained by him in East Africa and which 

 were deposited in the Museum. The collection of Chimpanzees in this 

 Institution is the largest in the world, and exhibits the wonderful indi- 

 vidual variation that exists in the skulls and coloring of the skins of 

 these apes ; variations that serve more to perplex than to enlighten the 

 observer on the mystery of species, and what really constitutes such a 

 rank. In Dresden the Author's thanks are due to Dr. A. Jacobi, the 

 Director of the Museum, who aided him in becoming familiar with 

 certain important types in the collection under his charge ; and in the 

 splendid Museum in Vienna, to the Director Dr. F. Steindachner, and 

 custodian Dr. L. R. Lorenz, the Author is greatly indebted for many 

 attentions and assistance in examining the collection which comprises 

 the examples procured by Natterer during his sojourn in Brazil, as 

 well as important specimens of the Gorilla procured by Du Chaillu in 

 the Gaboon, West Africa. 



To Professor Dr. R. Hertwig, Director; Dr. W. Leizewitz and 

 Dr. C. Hellmayer, Custodians of the Zoological Museum, Munich, in 

 the collection of which are contained Spix's types, and a very large 

 number of examples of the crania of Bornean Ourangs obtained by 

 Selenka, the Author is under many obligations for their courtesy dur- 

 ing his sojourn in their city. In Frankfort-on-the-Main, by the cour- 

 tesy of the Acting Director, Dr. Drevermann of the Senckenbergian 

 Museum, the Author was enabled to examine the skins and skeletons 

 of Pseudogorilla mayema? which, from the disappearance of the 

 type, are the only specimens known in Europe at the pfesent time. 



