348 ESSAY ON CLASSIFICATION. 



necting or osculant circles. 1 The number, therefore, as 

 many erroneously suppose, is not five, but ten. This is 

 quite obvious ; and our opinion on this point is confirmed 

 by the author himself in the following passage, when 

 alluding to his remarks upon the whole : ' The foregoing 

 observations, I am well aware, are far from accurate, but 

 they are sufficient to prove that there are five great circu- 

 lar groups in the animal kingdom, each of which possesses 

 a peculiar structure; and that these, when connected by 

 means of five smaller osculant groups, compose the whole 

 province of Zoology.' Now these smaller osculant groups 

 are to be viewed as circles; for, as it is elsewhere stated, 

 'every natural group is a circle more or less complete/ 

 This, in fact, is the third general principle of Mr. M'Leay's 

 system ; and he has exemplified his meaning of a natural 

 group in the above diagram, where all animals are arranged 

 under five large groups or circles, and five smaller ones. 

 Let us take one of these groups, the Vertebrata. Does 

 that form a circle of itself ? Yes ; because it is intimated 

 that the Eeptiles (R&ptilia) pass into the Birds (Aves); 

 these, again, into the Quadrupeds (Mammalia}; Quadru- 

 peds unite with the Fishes (Pisces); these latter with the 

 amphibious Eeptiles; and the Frogs bring us back again 

 to the Reptiles, the point from whence we starred. Thus 

 the series of the vertebrated group is marked out, and 

 shown to be circular; therefore it is a natural group. This 

 is an instance where the circular series can be traced. 

 We now turn to one where the series is imperfect, but 

 where there is a decided tendency to a circle. This is the 

 Mollusca. Upon this group our author says : ' I have by 

 no means determined the circular disposition to hold good 



1 In the original diagram, as in merely indicated by the names ar- 

 that above, these five smaller circles ranged like rays between the five 

 are not represented graphically, but large circles. 



