ON THE ARRANGEMENT OF THE MAMMALIA. 187 



toes being soldered together, as the Horse, or connected together by a web, 

 as the Flamingo. Both orders present us with the greatest elongation of 

 muzzle, or facies ; witness, the Myrmecophaga, or Antelope, and Scolo- 

 pax ; and, also, the most depressed form of muzzle, witness, the Hip- 

 popotamus and Platalea. In both orders we have the most elongated claws, 

 witness, Megalonyx and Parra. Both orders afford us the swiftest ani- 

 mals in running, as the Horse and Tachydromus ; and the most pugnacious 

 on account of love, as the Bull and Machetes." 



Somewhat subsequently to Mr. Vigors, Mr. Swainson directed his atten- 

 tion to the circular system ; but with results, in many respects, widely 

 different from those arrived at by the preceding naturalist. The princi- 

 ples of his circular system are detailed, at some length, in the Fauna 

 B or eali- Americana (vol. ii. Birds). Mr. Swainson states his theory as 

 follows : 



" First. Every natural series of beings, in its progress from a given 

 point, either actually returns, or evinces a tendency to return, again to that 

 point, thereby forming a circle. 



" Secondly. The contents of such a circle, or group, are symbolically 

 represented by the contents of all the other circles in the same class of 

 animals ; this resemblance being strong, or remote, in proportion to the dis- 

 tance or proximity of the groups compared. 



" Thirdly. The primary divisions of every natural group, of whatever 

 extent or value, are three ; each of which forms its own circle." The 

 three groups consist of one typical, one sub-typical, and one aberrant. 



The former writers, Mr. Mac Leay and Mr. Vigors, consider the cir- 

 cumstance of a group returning from any given point, into itself, as the 

 test of its being truly natural ; not so Mr. Swainson : he considers 

 that a group, if natural, must represent, and be again represented by, 

 other groups. " Without some other test," he observes, " for a natural 

 group, than the mere circumstance of its returning into itself, or even 

 its simple parallelism with a contiguous group, I consider demonstration 

 not to have been attained. The theory of representation thus steps in, 

 and at once dispels the illusion, or demonstrates the correctness of the 

 series." He also advocates the direct union of typical groups, which 

 the quinary modification of the circular system does not recognise ; and 

 he states the " direct union of typical groups, without the intervention of 

 those which are aberrant," to be " an unquestionable property of natural 

 arrangement." 



Again, the mode of synthetical investigation, which is followed by the 

 author of the Horce Entomologicte, and by the great advocates of the 

 quinary arrangement, is regarded by Mr. Swainson as inadequate to accom- 

 plish the end in view. " I soon found," he says, " that, although this 

 theory (the quinary) would explain much that I desired, it would not ex- 



