BIRDS. 171 



V. NATATORES, dividedinto three tribes, viz. TELEOPODES, ATELEO- 

 PODES, and PTILOPTERI. The first tribe includes the families Syn- 

 dactyli, Urinatores, Dermorynchi, and Pelagii ; the second, Si- 

 phorini and Brachypteri ; the third Sphenisci. 



Mr N. A. Vigors, in a paper in the 14th volume of the Lin- 

 naen Transactions, founding upon a principle discovered by Mr 

 Macleay, the author of Horce Entomologicce, proposed a new 

 arrangement of birds, according to their natural affinities. " I 

 discovered (says he) as I advanced, that the larger or primary 

 groups were connected by an uninterrupted chain of affinities ; 

 that this series or chain returned into itself ; and that the groups 

 of which it was composed preserved in their regular succession 

 an analogy to the corresponding groups or orders of the conti- 

 guous classes of zoology. I equally detected the existence of 

 the same principle in most of the subordinate divisions, even 

 down to the minutest, to a degree at least sufficiently extensive 

 to afford grounds for asserting its general prevalence." P. 399. 



This chain of affinities, Mr Vigors conceives, takes always a 

 quincunx form ; so that in the class of Birds, if the five orders 

 into which he arranges them, viz. Raptores, Insessores, Rasores, 

 Grallatores, and Natatores, were placed in connected circles, 

 round a common centre, they would be found to be mutually 

 connected together. 



INSESSORES. 



RAPTORES. RASORES. 



AVES. 



NATATORES. GRALLATORES. 



The same connection is found to take place between the mi- 

 nor subdivisions, when arranged in a similar form. For instance, 

 in his second order INSESSORES, composed of five tribes, the 

 arrangement stands thus : 



CONIROSTRES. 



DENTIROSTRES. SCANSORES. 



INSESSORES. 

 FISSIROSTRES. TENUIROSTRES. 



Each of these tribes again is further divided into five families, 

 which, when placed in the same order, are found to be similarly 

 connected. 



As a further confirmation of Mr Vigors's theory, it may be 



