INTRODUCTION. 



rilHIS work was originally intended to be confined to a description of the Zoolo- 

 -*- gical Eesults of the two Yunnan Expeditions. In working them out, how- 

 ever, I was led to examine certain Asiatic genera as a whole ; and having done so, I 

 have embraced the opportunity to incorporate these observations along with the 

 results of the Expeditions, as they were founded, in the majority of cases, on the 

 actual comparison of the types of the individual species ; hence the descriptions of 

 the various species of Sylobates, Macacus, Semnopithecus^ Sciurus, ^c. 



In the same way, in dealing with the Cetacean of the Irawady, I. was led to 

 compare it with its near ally occasionally found in the estuary streams of the 

 Ganges, and, as this latter form had never been fully described, to include an account 

 of its placentation and anatomy generally alongside of the former. Moreover, as 

 both of these Cetaceans are more or less fluviatile in their habits, I was further 

 induced, from the circumstance that I had already devoted some time to an examin- 

 ation of the placentation and anatomy of Flafanista, to add a history of its distri- 

 bution and structure to that of the two former, and thus to give a Monograph of 

 the known fluviatile Cetacea of Asia. 



It will be observed that for special sections of the work I am indebted to 

 naturalists who are recognized authorities in the departments which they describe. 



It is necessary that I should here give a short account of the two Expeditions, 



in order to bring out the difficulties with which I was beset as a naturalist, and 



which, to my great regret, were of so formidable a nature, that they restricted my 



investigations within the narrowest limits in a country the fauna of which is 



extremely rich and all but unknown. 



The Eirst Expedition was despatched in the end of 1867 from Calcutta, and 

 returned in November 1868; and the Second Expedition left Mandalay on the 

 3rd January 1875, and returned thither on the 10th March of the same year. 



By the permission of the Trustees of the Indian Museum, my services were 

 placed at the disposal of the Government of India to accompany the two Missions as 

 Naturalist and Medical Officer. 



With regard to the scope of the Eirst Expedition, it was intended that it should 

 penetrate from Mandalay into the Province of Yunnan, via Bham6, and, if possible, 



