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cimen of which is now in the Society's Gardens, has an extensive 

 range, being found on both banks of the Amazon and Rio Negro. 

 The C. torquatus, a white-collared species, is found only on the 

 Upper Rio Negro, and the C. personatus on the Upper Amazon. 



Of the curious Nocturnal Monkeys forming the germs Ni/ctij)ithe- 

 cus there are two species in this district ; one, which appears to be 

 the N. trivirgatus of Humboldt, is found in the district of Ecuador, 

 west of the Upper Rio Negro ; the other, closely allied, probably the 

 N.felinus, on the Upper Amazon. Their large eyes, cat-like faces, 

 soft woolly hair and nocturnal habits render them a very interesting 

 group. They are called " devil monkeys " by the Indians, and are 

 said to sleep during the day and to roam about only at night. I 

 have had specimens of them alive, but they are very delicate and 

 soon die. 



Of the Marmozet Monkeys there are three species, though none 

 of them have the characteristic tufts of hair on the head. Each 

 species seems to be confined to a very limited tract of country. The 

 Jacchus tamarin is found only in the district of Para, where it is 

 abundant. The J. bicolor, a pretty grey and white species, I have 

 only seen on the Guiana side of the Rio Negro near the city of Barra. 

 Another species entirely black, with the face of bare white skin, 

 inhabits the district of the Upper Rio Negro. It appears to be 

 quite new. 



The last three genera appear to be to a great extent insectivorous, 

 and I am inclined to think they also devour small birds and mam- 

 malia. At least those I have had alive would attempt to pull into 

 their cages any of my small birds which passed near. The little 

 black Jacchus last mentioned was particularly savage. He once 

 seized a large parrot by the neck, pulled him into his cage, and bit 

 out a large piece from his bill, and would probably have destroyed 

 it, had I not opportunely come to the rescue. Two other small 

 birds which approached too near his cage he seized and completely 

 devoured. 



I will now make a few remarks on the geographical distribution of 

 these animals. 



In the various works on natural history and in our museums, we 

 have generally but the vaguest statements of locality. S. America, 

 Brazil, Guiana, Peru, are among the most common ; and if we have 

 "River Amazon" or "Quito" attached to a specimen, we may 

 think ourselves fortunate to get anything so definite : though both 

 are on the boundary of two distinct zoological districts, and we have 

 nothing to tell us whether the one came from the north or south of 

 the Amazon, or the other from the east or the west of the Andes. 

 Owing to this uncertainty of locality, and tbe additional confusion 

 created by mistaking allied species from distant countries, there is 

 scarcely an animal whose exact geographical hmits we can mark out 

 on the map. 



On this accurate determination of an animal's range many interest- 

 ing questions depend. Are very closely allied species ever separated 

 by a wide interval of country 1 What physical features determine 



