CHAPTER IX. 
ON CONCENTRIC CIRCLES AND CONVERGING RADII. 
I have endeavoured, in the preceding chapters, to ex¬ 
plain my views of the System of Nature by a synthetical 
grouping of animals : beginning with man as a centre, I 
have added the various groups of animals around him in 
a series of rings : these rings amount to eight in number, 
besides the central area, which I suppose occupied by 
man and those quadrumanous animals which most nearly 
approach him; and the exterior groups being limited by a 
series of concentric circles, each increasing in diameter 
as the animals, whose limit it circumscribes, are supposed 
to recede in structure from the normal and central form of 
man. In accordance with certain defined but unproved 
propositions, the animals supposed to stand in these eight 
different degrees of approximation to man are thus enu¬ 
merated. 
Within the first circle are the Cebidae or American mon¬ 
keys, the Bradypida? or sloths, and the LemuridaB or lemurs ; 
within the second circle, the Galeopithecidae or flying le¬ 
murs, and the Megatheriidae or fossil sloths : these five 
groups, with the Hominidae, as the central group has been 
termed, constitute the higher group which has been usually 
