The Brain in the Oribatidse, &c. By A. B. Michael. 281 
a series of 191 cases the maximum weight of the brain in the adult 
female was 56 oz. and the minimum 31 oz. The mean weight, 
according to Bischoff, of the adult male brain is 1358 grm. and that 
of the adult female 1220 grm. In children at birth the average 
weight according to Boyd is, male 11*65 oz. and female 10 oz., and 
the proportion of brain to body at birth according to Tiedeman is 1 to 
5*85 in the male and 1 to 6 * 5 in the female ; but in the adult the 
proportion is very much less ; in persons dying after prolonged illness 
probably about 1 to 35 ; the normal ratio, however, in adult healthy 
persons is probably about 1 to 45 = 2*22 per cent. 
The brain of the Acarina is too small an object to be weighed, but 
the proportionate weight of the brain to the body would doubtless be 
larger than the proportionate bulk, because the brain is a solid organ, 
whereas the body contains large cavities; it would seem therefore 
that as the human brain averages about 2*22 per cent, of the weight 
of the body, and the brain of Gamasus terribilis measures about 
1*61 of the bulk, the brain of that creature, which may be con- 
sidered a fair specimen of its family, cannot be very far short of the 
proportion of the human brain. 
Note on the Mode of Calculating the Volumes. 
By E. M. Nelson, F.R.M.S. 
It would seem that the best course to pursue in arriving at the 
volumes of these irregularly shaped bodies would be to divide 
them up into more or less regularly shaped portions. Thus, for 
example, if we take Cepheus latus and cut off the rostrum, i.e. the 
pointed end, we shall have two fairly regular figures to deal with. 
The volume of the larger portion may be assumed to lie between the 
volume of an inscribed prolate spheroid and a circumscribed elliptical 
cylinder. If, therefore, the mean of the volumes of these two figures 
be taken the result cannot be far from the truth. With regard to the 
conical end (rostrum), its volume will be larger than a right cone of 
the same height because of its blunted end, it might therefore be 
taken as a half instead of as a third of its circumscribing cylinder. 
Assuming that the length of the conical end is one-sixth that of the 
whole body, the formula will be as follows : — 
Let Z be the length, b the breadth, d the depth, and Y the 
volume, then 
5 l 
b + d 
= -A ; f- — o— ; ff=b.d. 
e . - : 
4 ’ 
h = e.f. 
-i 
m = 
9 + h 
2 
Y = 
