A74 BUMPUS. iVor. Xai 
I wish that alcoholic “ mud-puppies ” presented some striking 
coloration, like the spots of Diemyctylus or Amblystoma, so 
that one might detect any tendency towards color variation 
in specimens presenting skeletal instability ; few animals, how- 
ever, are more alike externally than preserved specimens of 
Necturus. 
Section VIII. 
The question may arise: Are variations in the position of 
the pelvis correlated with sex, or, if not directly dependent 
upon the sex, does one sex show a greater tendency towards 
skeletal variation than the other? 
It is frequently the case when a large number of individuals 
of a single species are collected that the males predominate, 
but in the present collection, as will be seen by counting the 
indices of sex at the top of Plate C, there are thirty-seven 
males and sixty-three females. There should be, then, if varia- 
tion is equally distributed among males and females, nearly 
twice as many abnormally placed pelves among the females as 
among the males. In fact, however, of the thirty-six homeeotic 
specimens, only nine occur among the males, while twenty-seven, 
three times as many, occur among the females. 
It is, I think, quite generally believed that males are much 
more subject to variation than are females. Montgomery (96) 
in his recent paper on “Organic Variation”’ states that “the 
dimensions of birds are more variable in the males than in the 
females,’’ and that “it is not impossible that in birds, as in man, 
the female may be more conservative and less progressive than 
the male.” This of course recalls Brooks ('83) and Geddes and 
Thomson ('90), though we should not forget that males are fre- 
quently larger among birds and mammals, and thus offer an 
increased amplitude of variation, and that males are, moreover, 
frequently provided with many and variable secondary sexual 
characters whose development is directly dependent upon the 
activity of the proper sexual glands, and are hence subject to 
considerable variation. 
Among Amphibia, however, it has been many times shown 
that the male may assume certain of the duties which are 

