510 Zoological Society : — 



sisting in fact of two separate tables of contents, one giving a list of 

 the subjects treated of in the order in which they occur in the sub- 

 sequent pages ; whilst the other or " Physiological Index " takes the 

 different organs or their functions as the basis of its arrangement, 

 and furnishes references to the particular paragraphs in which their 

 nature in the various groups of animals is described, thus enabling 

 the reader to trace any one function or organ from its first appearance 

 to its full development. 



PROCEEDINGS OF LEARNED SOCIETIES. 



ZOOLOGICAL SOCIETY. 



May 8, 1855. — G. R. Waterhouse, Esq., in the Chair. 



Mr. Gould exhibited a portion of a collection of birds formed by 

 Mr. Hauxwell in a district lying on the eastern side of the Peru- 

 vian Andes, in the neighbourhood of the River Ucayali, one of the 

 tributaries of the Upper Amazon. Mr. Gould observed, that the 

 exploration of this particular district had been one of the earliest 

 objects of his own ornithological ambition, but that until within the 

 last few years no naturalist had visited it. The splendid collection 

 sent by Mr. Hauxwell, of which the birds exhibited to the Meet- 

 ing formed a part, fully bore out the anticipations entertained by 

 Mr. Gould, that when explored it would prove one of the richest 

 and most interesting ornithological districts with which we are ac- 

 quainted. 



Amongst the birds exhibited were some Cotingas, differing from 

 the ordinary species found in the lower countries of Brazil, and 

 remarkable from the splendour of their colouring, together with spe- 

 cies of Phoenicercus, Rhamphocelvs, &c., of the most dazzling bril- 

 liancy. As a contrast to these, INIr. Gould exhibited a series of dull- 

 coloured Thamnophili, also contained in this collection, and remarked 

 that this striking difference in the coloration of birds inhabiting the 

 same locality was due almost entirely to their different degrees of 

 exposure to the sun's rays ; the briUiantly coloured species being 

 inhabitants of the edges of the forests, where they fly about amongst 

 the highest branches of the trees, whilst the others form a group of 

 short-winged insectivorous birds, which inhabit the low scrub in the 

 heart of the dense humid jungle, where the sun's rays can rarely, 

 if ever, penetrate. 



Mr. Gould also remarked, that the coloiu's of the more brilliant 

 species from the banks of the Ucayali, a district situated towards the 

 centre of the South American continent, were far more splendid than 

 those of the species representing them in countries nearer to the sea, 

 and from this circumstance he took occasion to observe that birds 

 from the central parts of continents were always more brilliantly 

 coloured than those inhabiting insular or maritime countries. This 

 rule applies equally to birds of the same species, the Tits of Central 

 Europe being far brighter in colour than British specimens. Mr. 



