Linneun Transactions. 265 



family closely approximating in manners and in anatomy to the 

 Gallinaceous group. Between the Grallatores and the Natatores 

 it is almost unnecessary to point out any connecting link, since 

 they approach each other by such gradations as to render it diffi- 

 cult to fix the exact limits of each. We may therefore pass on 

 at once to the concluding link in this chain of affinities, which is 

 one that it might appear almost impossible to supply. Nothing 

 indeed can be more dissimilar than the habits of the Natatores 

 and those of the Raptores ; yet these it becomes necessary to 

 unite in order that the circle may be completed. Frequenting 

 different elements, and performing totally opposite functions in 

 nature, the extreme discrepancy in the structure of their feet 

 renders it difficult to conjecture how any modification of it can 

 bring them into contact. Such a modification is however met 

 with in the genus Tachi/peies^ Vieill., the Pelecamis Aquilusy 

 Lin. Essentially natatorial in the character of its feet, their 

 organization is so weakened and modified as to deprive it of the- 

 power of swimming ; while its surprising strength and expansion 

 of wing point it out as an inhabitant of the air. Attached exclu- 

 sively to the ocean, on the surface of which it is, however, in- 

 capable of resting, it thus preserves some connexion with the 

 clement inhabited by the other Natatores, and is united to the 

 Raptores by the predaceous habits which it pursues at immeasu- 

 rable distances from the shore. 



Into the next and most extensive portion of Mr. Vigors' en- 

 quiry, the arrangement and affinities of the minor groups of which 

 his orders are composed, it would be impossible to follow him 

 with sufficient detail to render our notice explanatory of hia views ; 

 and we must therefore unwillingly confine ourselves to the mere 

 enumeration of the tribes or families referable to each. The 

 Raptores are perhaps less known than any other grand division 

 of the class ; the Vulturidce, Fakunidw, and StrigUhv, being in 

 fact the only families with which we are yet sufficiently ac- 

 quainted ; a fourth family will probably be supplied by the New 

 World, which is known to possess Raptorial Birds that have not 

 hitherto been properly described ; and the fifth may be furnished 

 by the Gypogerunidce. The Inscssores^ exceeding considerably 



