1895.] Zoology. 1013 
the oviducts of the female, behind the vent, is covered by a larger 
scale (s), a foricula (a diminutive shutter), which opens to the right on 
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dextral (3) and to the left on sinistral individuals (2). Evidently 
copulation is effected by a right male at the left side of a left female, 
and by a left male at the right side of a right female, the anal (p ) of 
the male being turned so as to bring its tip under the free edge of the 
foricula (s) into the mouth of the oviducts. 
From the specimens examined it would appear, at sight, as if the 
male sex was eventually to become dextral and the female sinistral, 
and as if by selecting rights or lefts one might exclusively raise either 
rights or lefts as he chose; but the proportions of the sexes, and of 
dextral and of sinistral of each sex, in the progeny are really deter- 
