ORGANS FOR SPERM-TRANSFER 289 
many cases the annuli of the females were artificially cleared 
out so that any new plugs would have been seen. 
Among these cases there were males that alternately used the 
fifth left and right legs in crossing, though some had only the left 
series of stylets and others the right; the leg being crossed on the 
side where there was no stylet and on the side where there was a 
stylet. And these same cases were attempting conjugation with 
females that were of both kinds, right and left forms, so that there 
was no agreement between the kind of annulus and the fifth leg 
used. 
In only one case was there any sperm seen and this was seen 
twice in successive conjugations of the same male that seems to 
have been peculiar. This sperm lay in pseudo spermatophores, 
8 mm. long, upon the telson of the female under the left stylet, 
and probably escaped from some imperfection of the closure of 
the triangle. 
While it was not found out why there was this apparent inability 
tocomplete sperm transfer while the stylets of one side were miss- 
ing it is thought that this is not due to the need of usingsperm 
from both sides of the body at each conjugation but rather to the 
mechanical factor that the two sets of stylets are always applied 
to one another so firmly as to hold the tips of the stylets at the 
annulus, so that when one is absent the tip of the remaining one 
lacking the usual support cannot be readily brought to the middle 
line of the body. Moreover it is possible that the triangle will 
not be well applied to the orifice unless the fellow triangle be there 
to shove against it, as both are packed in side by side between the 
necks of the first stylets. 
SUMMARY 
Though the sperm of the crayfish, Cambarus affinis, is injured 
by exposure to water, it is transferred from the male to the female 
under water and stored up in an external pouch. 
The part played by the female in this insurance against injury 
in transit has been elsewhere described. 
