based on the principle of Cephalization. 339 
there is some correspondence between average size of structure 
and strength of life-system. But a comparison of the typical of 
the former with the eg eee of the latter leads to very 
false re 
An Nai ep to the right ratio is obtained from a com: * 
parison of the degradational species of eac ut this is of 
no importance in its bearing on the question, ‘since vegetative 
growth is apt to . BN the greatest proportional enlargement to 
the lowest specie 
These facts teach that relative size of body, or of brain, is no 
necessary test of relative rank. The ratio, in bulk, of 1:8 between 
the brain of an average Man and that of a gorilla tells nothing 
of the actual difference of life- -system, or of brain-power. At 
page 70, in the last volume of this Journal, the relative lineal 
dimensions of Microsthenes and Megasthenes is estimated at 
1:4, which gives, for the relative bulk, 1:64. If this be the 
typical ratio between the life-systems of the highest Microsthenes 
and highest Megasthenes, surely that between the highest Megas- 
thenes and normal Man—he constituting a distinct order (see p. 
341)—must be at least vi great. 
The same ratio of 1: 4, as shown by the writer, is that for the 
mean size, lineally, of poereanalch and Decapods, under Crus- 
ceans. In two cases, then, consecutive orders differ by a like 
ratio, or approximately so, in dimensions. As has been re- 
marked, deductions from mere size may be very erroneous; yet 
there is no reason, in either of the above cases, to suppose the 
Tatio of life-systems less than that thus indicated. May not, 
therefore, some similar ratio exist between other analogous con- 
secutive orders where size does not manifest it,—as, for nee: 
. 
not 
salen bn but classes ? ite results may flow fron following 
out the = here touched upon. 
he preceding explanations, I proceed to exhibit some of 
the elaine of the higher groups in zoological classification, 
as they appear in the light of this subject of cephalization. 
3. Classification of Animals. 
1. Subkingdoms,—Of the be eis, i first 
by Cuvier and since by most zoologists, the Vertebrate, Articu- 
and Molluscan are ty ical, or ak “the true animal-type, 
1 ot being plant-like in ty] sljagem the 
ely pane a betatypic and ee at c simply as number- 
. 
Am. Jour. Sc1.—Seconp Santis, Vou. XXXVI, No. 107.—Nov., 1863, 
. 44 
