We see this especially in the third case, where the presence of a solitary female in a family of twenty-six is due to the somewhat larger diameter of the corresponding Snail-shell.
There would still remain the inverse permutation: to obtain only females and no males, or very few.

The first permutation makes the second seem very probable, although I cannot as yet conceive a means of realizing it.

The only condition which I can regulate is the dimensions of the home.

When the rooms are small, the males abound and the females tend to disappear.

With generous quarters, the converse would not take place.