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Miscellanea 
Entirely lacking in definite quantitative evidence in its favour, this general point of view 
regarding the relative variability of the sexes has been widely prevalent among biologists. Now 
it is obvious that if this generalization is a valid one the general principle involved should 
find expression, in some measure at least, in all sexual organisms. AVhether it does or not, 
may be determined in a perfectly definite way by application of modern biometrical methods 
to the analysis of data collected by actual measurement of various characters in individuals 
of the two sexes. 
As a small contribution toward such data, I have determined the chief variation constants 
of some very carefully collected material presented by Dr A. Porta *. The published data give 
measurements of fifteen similar characters of 84 males and 84 females of the beetle Carahus 
aumtiis, L. The characters measured were the following : 
(1) Length of body. (2) Maximum breadth of body. (3) Length of head. (4) Width of 
head. (5) Length of prothorax. (6) Width of prothorax. (7) Length of antenna. (8) Length 
of first four joints of antenna. (9) Length of anterior leg. (10) Length of median leg. (11) Length 
of posterior leg. (12) Length of tarsus of anterior leg. (13) Length of mandible. (14) Length 
of elytra. (15) Length of first joint of antenna. 
The measurements are expressed in millimetres. 
In the table presented herewith, we have given, in the first column, the mean of each 
several character with its probable error. In the second column are likewise arranged the 
standard deviations from the mean of each character with their probable errors. In the third 
column are given the coefficients of variability and their probable errors. 
From the evidence of the means of the fifteen characters measured, four — the length of 
posterior leg, length of anterior leg, length of tarsus of anterior leg, and total length of antenna 
— are so nearly equal in length that any difference is more than covered by the probable error. 
These characters can hardly be held to possess any secondary sexual significance. In these 
four characters, whose mean size is the same in both male and female, there is, furthermore, 
no evidence that one sex varies any more than the other. In the case of the anterior leg, the 
female shows a slight tendency to vary more than the male. This difference is not significant, 
however. 
In all the other characters measured the mean is distinctly larger in the female than in 
the male, and we may safely assume that these differences represent a greater or less degree 
of secondary sexual differentiation. In four of these characters — length of first four joints of 
antenna, length of prothorax, length of head, and width of body — the female shows a higher 
index of variability than the male. In none of these, however, is the higher rate of variability 
of real significance, as in no case does it exceed double the probable error. 
In the seven remaining characters the male shows a tendency to be more variable than the 
female. In four of these — length of mandible, length of first joint of antenna, length of body, and 
width of prothoi'ax — the excess of variability is so slight as not to be appreciable. It is much 
more than offset by the size of the probable error. In the last three characters the male is 
probably significantly more variable than the female. In the length of elytra, length of median 
leg, and width of head, the excess of variability in the male is practically three times the 
probable ei-ror for the same. 
On account of the small numbers of individuals taken in each case little emphasis can be 
laid upon the details of the results noted. It is worthy of consideration, however, that the four 
characters of equal size in each sex are equally variable, and that in the eleven remaining 
characters when there is a difference in size between the two sexes, only three show a greater 
variability in the male than in the female. 
The general conclusion can only be, that, so far as the present data indicate, there is no 
uniform tendency for the individuals of one sex to be more variable than those of the other 
sex in the beetle, Carabus auratus, L. 
* Porta, A., "Le Differenze sessuali seeondarii quantitative nel Carabus auratus, L." Bull. Soc. 
Entoni. Ital. Ann. 34, 1902. 
