72 REPORT— 1844. 



On two New Species of the Family LaurinecBf from the Forests of Guiana, 

 By the Chevalier Schomburgk. 



The first is a tree which affords timber which is brought to England, and known 

 by the name of Greenheart. This tree was found, by Dr. Bodie, to possess febrifugal 

 properties, and Dr. Maclagan has published an account of two new alkaloids which 

 he had obtained from it by chemical processes. These alkaloids may be used instead 

 of quinine. The second tree has long been known, and yields an aromatic fruit, known 

 by the name of the Accawai nutmeg, and is extensively used in Guiana as a remedy 

 in diarrhoea, dysentery, and other intestinal diseases. The author succeeded in ob- 

 taining flowers and seeds, and had found this tree to be a species of Acrodiclidium, 

 to which he has given the specific name Camara. It appears to be restricted to the 

 sandstone mountains of Roraima, between the fifth and sixth parallel of north 

 latitude. 



Mr. Schomburgk exhibited dried specimens and drawings of most of the plants he 

 described, as also of the Strychnos toxifera, a plant which produces the true Wouraii 

 poison of Guiana. 



The Chevalier Schomburgk read a paper on the Forest Trees of British Guiana, and 

 their use in civil and naval architecture. This paper was illustrated by a great number 

 of polished specimens, and some of them possessed extraordinary beauty of marking. 

 The author also exhibited a specimen of the trunk of the Aspidosperma excelsum, 

 which grows in the form of a fluted column ; and drew attention to the nest of the 

 Rock Manakin, or Cock of the Rock (Rupicola elegans) ; and to the head of the largest 

 freshwater fish known, the Sudis yigas of Cuvier, both of which he had brought 

 from Guiana. 



On some Peculiarities in the Flight of Birds, especially as that is influenced in 

 some Species by the power they possess of decreasing and adjusting their 

 own specif c gravity. By Thomas Allis. 



Birds require the centre of gravity to be placed immediately over the axis of motion 

 for walking, and beneath it when flying ; when suspended in the air their bodies natu- 

 rally fall into that position which throws the centre of gravity beneath the wings. 

 The axis of motion being situated in a different place in the line of the body when 

 walking from that which is used when flying, the discrepancy requires to be com- 

 pensated by some means in all birds, in order to enable them to perform flight with 

 ease. Raptorial birds take a horizontal position when suspended in the air, and the 

 compensating power consists in their taking a more or less erect position when at 

 rest. Another class, including the woodpeckers, wagtails, &c., take an obUque posi- 

 tion in the air ; with these the compensating power consists in their cleaving and 

 passing through the air at an angle coincident with the position of the body, and per- 

 forming flight by a series of curves or saltations. 



Natatorial birds sometimes need very extended flight ; they take a very oblique 

 position in the air ; they have the ribs greatly lengthened, the integuments of the 

 abdomen are long and flexible, which enables them greatly to enlarge the abdominal 

 portion of their bodies by inflating it with air ; this causes a decrease in the specific 

 gravity of that part and raises it to a horizontal position ; the compensating power 

 consists in the posterior half of the body becoming specifically lighter, while the spe- 

 cific gravity of the anterior half remains unaltered. 



I 



Mr. Babington exhibited to the Section specimens of three plants which had been 

 added to the Hst of British plants during the summer of 1844. 



1. Alsine stricta, discovered on Widdy-bank Fell inTeesdale, Durham, by Mr. James 

 Backhouse of York and a small party of botanists. It occurred in small qucintity, 

 but from the nature of the locality and the plant inhabiting the northern parts of 

 Europe, it must be considered as an aboriginal native of England. 



2. Carduus setosus, growing near the shore of the Frith of Forth in the neighbour- 

 hood of Culross. As it is a native of the countries to the north-west of the Black 



