348

ESSAY ON CLASSIFICATION.

necting or osculant circles. 1 The number, therefore, asmany erroneously suppose, is not five, hut ten. This isquite obvious; and our opinion on this point is confirmedby the author himself in the following passage, whenalluding to his remarks upon the whole: ‘ The foregoingobservations, I am well aware, are far from accurate, butthey are sufficient to prove that there are five great circu-lar groups in the animal kingdom, each of which possessesa peculiar structure; and that these, when connected bymeans of five smaller osculant groups, compose the wholeprovince of Zoology / Now these smaller osculant groupsare 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’ssystem; and he has exemplified his meaning of a naturalgroup in the above diagram,where all animals are arrangedunder five large groups or circles, and five smaller ones.Let us take one of these groups, the Yertebrata. Doesthat form a circle of itself 1 Yes; because it is intimatedthat the Reptiles (. Reptilia ) pass into the Birds ( Aves );these, again, into the Quadrupeds (Mammalia); Quadru-peds unite with the Fishes ( Pisces); these latter with theamphibious Reptiles ; and the Frogs bring us back againto the Reptiles , the point from whence we started. Thusthe series of the vertebrated group is marked out, andshown to be circular; therefore it is a natural group. Thisis an instance where the circular series can be traced.We now turn to one where the series is imperfect, butwhere there is a decided tendency to a circle. This is theMollusca . Upon this group our author says: ‘ I have byno 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 fiveare not represented graphically, but large circles.