62 



Mr. Gray also exhibited several specimens of the genus Rhyn- 

 chcBa, Cuv., and pointed out from among them two distinct species, 

 which may be thus characterized: 



Rhynch^a Capensis, Sav. Rhynch. remigibus anguMis,_fasciis 



latis flavis sex notatis, infra griseis, nigro-vermiculatis,Jiavoque 



Jasciatis ; secundariarum macidu pogonii externi, fascidque po- 



gonii interni,Jlavis. 



Long, corporis 9|^ unc. : tarsi, 11^ lin. : digit! unguisque medii, 



20|lin. 

 RHYNCiTiEA PICTA. Rliyuch. remigibiis suhlatis, externis Jlavo 

 late 1 -Jasciatis, injrh griseo nigroque vermiculatis, inlerno obso- 

 lete flavn -Jasciato : secundariarum apicibus, macidd iiltimdJascicB- 

 formi pogonii externi, Jascidque pogonii interni, albis. 

 Long, corporis 10| unc. : tarsi, 19^ lin. : digiti niedii, 19 lin. 

 The wing-coverts of both species are spotted with yellow in the 

 young state ; and in the adult state are metallic olive with black 

 bands. 



Mr. Gray added that the three figures of birds of this genus which 

 were published by Buffon, and which had of late years been re- 

 garded by M. Temminck and by M. Cuvier as representing various 

 states of but one species, were none of them sufficiently correct in 

 the details to enable him to refer either of the present species to the 

 representations given in the 'Planches Enlurainees;' but that the 

 figure of ihe Rhynchcca C.cpensis given by Savigny in the ' Oiseaux 

 d'Egypte' [tab. 14. fig. 2.], furnished a faithful representation of 

 the first species exhibited by him. He had not, however, obtained 

 this bird from the Cape of Good Hope, his specimens being from 

 India and China. The second species, Rhynchcea picta, he had re- 

 ceived from Africa as well as from India and China. 



Mr. Vigors called the attention of the Committee to the Frigate- 

 bird {Tachypetes Aquilus,Viei\l.) , and dwelt upon those peculiarities 

 of its organization which point out its station in the series of na- 

 tural affinities that connect the orders of birds. Although it possesses 

 the webbed feet which constitute the technical character of the Na- 

 tatorial Order, the weakness of its legs and their complete covering 

 of feathers preclude it from employing these members in the same 

 manner as the typical groups of the Swimming Birds ; while on the 

 other hand its great powers of wing and tail adapt it for powerful 

 and long-continued flight, and evidently connect it with the Rap- 

 torial Order, which it also resembles in its manner of taking its 

 food. It is in fact rather an inhabitant of the air than of the water; 

 and it has been believed that it derives support during its unlimited 

 flights not merely from the strength and expansion of its wings and 

 the singular mechanism of its tail, but also from the buoyant nature 

 of the inflated sac beneath its throat. A proof of the correctness of 

 the opinion that this pouch is really an air-sac, and that it is filled 

 with air, which passing througli the bones becomes rarified and ca- 

 pable of imparting a high degree of buoyancy, has recently been 

 obtained from the anatomical notes made by Mr. Collie, late Sur- 



