that connect the Orders and Families of Birds. 419 



Tachi/petes, Vieill., we find a still more immediate approach to 

 the Birds of Prey*, in their raptorial habits, their soaring and 

 aerial flight, and the rapid seizure of their prey without im- 

 mersing themselves in the waters whence they seek it. The last- 

 mentioned genus, Tachypetes, in particular, exhibits in its general 

 habits and structure the most conclusive evidence of this affinity, 

 and of its deviation at the same time from the Natatores. Al- 

 though for the most part it pursues its habits of rapine at immea- 

 surable distances from the shore, and derives its support exclu- 

 sively from the ocean, it is never known to rest upon its surface. 

 It does not possess in fact, to a sufficient extent, those glands 

 which by their oily secretions preserve the plumage of other 

 oceanic birds from the effects of the water ; while the extreme 

 disproportion of its hinder extremities deprives it of the power 

 of either swimming+ or walking. On observing the structure of 

 its legs we immediately detect this deficiency. Short, weak, 

 and feathered down to the toes, they are equally unsuited to the 

 land and the water. Its powers of motion and the characters by 

 which it maintains its station in nature are in fact centered in 

 its wings. Supported in its unlimited flights by the strength 

 and expansion of these members, and aided by the singular me- 

 chanism of its tail and the buoyant nature of the inflated sac 

 which distends its throat, it seems to be an inhabitant of the air, 

 rather than of the land where it resorts alone for the duties of its 

 nest, or of the water over which it only hovers for its prey. These 

 extraordinary and strongly marked characters, by which it thus 

 appears as it were to fluctuate between the confines of the two 



* Fregata avis Oculi nigri, acie acutissim^ et Jquilind. — Pedes breves ; ungues 



Vuhurini. — A ramis arborum in quibus resident difficulter admodum se levant: ve- 

 runi cum semel in sublime evolarunt, motu placido absque ulla fere alarum agitatione 

 aerem tranantes videas velut fluxu aut lapsu quodam, ad instar Milvorum. — Raii Sj/n. 

 p. 153. f See Linnean Transactions, vol. xiii. p. 3. 



VOL. XIV. 3 I orders 



