476 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
To trace the cavities within the exoskeleton of the annulus it was 
fixed in hot water or in alcohol, decalcified in Perenyi’s liquid or in 
hydrochloric acid, stained in borax-carmine and well washed in acid 
alcohol. It was then dehydrated and soaked in oil of cloves till trans¬ 
lucent. Such preparations were studied either whole or else cut into- 
thick slices and mounted in oil of cloves. 
Summary. 
1. In Cambarus afjinis the annulus ventralis of the female is shown 
to be an elevation of connective tissue covered by epidermis that forms, 
an exoskeletal pocket. This pocket has an open orifice at one end 
and a suture along its side. 
2. The male fills this pocket with sperm passed through the tubes, 
of the abdominal appendages and seals the orifice with secretion from 
the vas deferens. 
3. Within this pocket the sperm remains protected from the water,, 
sometimes for months, till the eggs are laid when it escapes through 
the hitherto closed suture along the ventral side of the pocket. 
4. There is evidence that the pocket is made to discharge at the 
right time by certain muscular contractions of the female. 
5. The sperms that spread from the suture over the surface of the 
annulus are still in the unexpanded form and have not yet been exposed 
to the action of water. 
6. The eggs were seen to leave the oviducts and to flow over the 
annulus enveloped in a mucus-like secretion of the ‘cement glands’ 
of the abdomen. 
7. Actual union of sperm and egg has not yet been made out, but 
if the eggs are fertilized at all (and we have no reason to assume that 
parthenogenesis occurs here) they are fertilized by the sperm from 
the annulus. 
8. In Cambarus virilis, the annulus differs from the above only 
in minor features of form and size. It is filled with sperm by like 
activities of the male. 
9. In Cambarus immunis the same is true. 
10. In Cambarus bartoni and in Cambarus clarkii the annulus 
differs from that of C. afjinis only in minor features of size and form 
and in C. bartoni it contained sperm. 
11. Presumably in all species of Cambarus the annulus contains 
an exoskeletal pocket used as a sperm receptacle. 
