474 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
While these annuli in group IV could be derived from the more 
simple form in group I there is nothing to suggest that the annulus of 
C. bartoni should belong in group III rather than in group IV. 
A careful study of the anatomy of the sperm pockets in the sixty 
odd species of Cambarus may be expected to furnish important aid 
in the grouping of these species. 
Three other problems connected with the annulus suggest them¬ 
selves for solution by experimental methods. The first is: Of what 
importance is the right- and left-handedness of annuli, as seen in four 
of the above five species and not unlikely to be found in all Cambari ? 
Does the male act differently toward the two forms of annuli as 
might be thought from the fact that in C. affinis the male stylets were 
supported sometimes by the right and sometimes by the left leg (An¬ 
drews, : 04) ? Again whether a female with right-handed annulus has 
young with right- or left-handed annuli, or some of each, should be 
determinable readily, since in C. affinis the young will breed within a 
year of hatching. 
The second problem is whether the ‘second form’ of male is really 
sterile and if so whether it be so from lack of sufficiently elaborate tools 
to fill the annulus. The ‘dimorphism’ of Cambari, discovered by 
Agassiz and described by Plagen, has been shown by Faxon (’84) to 
be a remarkable return of the perfect male, by moulting, to a more 
immature phase of development of male stylets. But at the same 
time the testes, as examined by Steele (:02), may well be inactive. 
Experiments as to the behavior of such males are needed. The 
third and fundamental problem upon which the two others bear, is, 
whether the male stvlets and the female annulus are eloselv adjusted 
to one another in each species or not. Experiments should at least 
decide whether the males of one species can fill the annuli of other 
species or not. 
Each species of Cambarus has its own form of male stylets and 
probably its own sculpturing, form, and position of orifice, and bend¬ 
ing of tube in the female annulus. xAre we to suppose that the long 
series of stylets depicted in the plates of Hagen or of Faxon are like 
specialized dentists’ tools, each specific sort to plug its appropriate 
cavity? Or is the exact shape of both stylets and annulus useless 
and a mere redundancy of form ? 
Awaiting experiments we may favor the latter view since an exam¬ 
ination of the stylets does not show, for instance, why they are long 
