RANK OF CIRCULAR GROUPS. 343 
groups that have been detected in the animal kingdom, 
whose affinities proceed in a circle, are Ninz, and they 
are thus designated, commencing from the highest and 
descending to the lowest: —1. Kingdom, 2. Sub-king- 
dom, 3. Class, 4. Order, 5. Tribe, 6. Family, 7. Sub- 
family, 8. Genus, 9. Sub-genus. 
(423.) It has been long customary, not only in 
science, but in ordinary parlance, to designate the three 
great divisions of ponderable matter as the animai, the 
vegetable, and the mineral kingdoms of nature; and, 
although it is not yet ascertained in what precise manner 
the vegetable, or, perhaps, also, the mineral kingdom*, 
describe their own circles, yet it is sufficient for our 
present purpose that the animal kingdom forms a cir- 
cular group, comprehending all beings which usually pass 
under that name, and all the ranks of groups we are 
about to describe. A kingdom, therefore, is the first 
and greatest circle ; and a sub-kingdom, as its name im- 
plies, is one of the primary divisions of the animal 
kingdom: of these, according to Mr. MacLeay, there 
are five, namely, 1. roe VERTEBRATA, or vertebrated 
animals, having an internal bony skeleton ; 2. roe AN- 
NULOSA, or annulose animals, as insects, where the body 
and legs are jointed, and the hardest parts are outside ; 
3. tHE Raprara, or radiated animals, which, like the 
star-fish, have the mouth in the middle; 4. raz Acrira, 
or the animaleules; 5. roe Monuusca, or shell-fish, 
whose nervous system is composed of several scattered 
masses or ganglions, united by nervous threads, and 
whose soft bodies are generally protected by a shell. The 
three last groups, the Mollusca, the Acrita, and the Ra- 
diata, are the aberrant divisions or sub-kingdoms of the 
animal kingdom ; which, if our conclusions be correct, 
form a circle more or less compiete among themselves. 
We shall not, however, in this part of our work, pro- 
ceed to alter the definite divisions from five to three, it 
being much better that the first of these numbers 
* See Northern Zoology, ii. Preface, p. liv. 
Zz A 
