PROCEEDINGS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



VOL. X, PP. 167-185. SEPTEMBER 16, 1908, 



THE SPERM-RECEPTACLE IN THE CRAYFISHES, 

 CAMBARUS CUBENSIS AND C. PARADOXUS. 



BY E. A. ANDREWS. 



IN some of the Crustacea all of the sperm that is to fertilize 

 the eggs is left by the male on the outside of the female and in 

 some others it is deposited in external receptacles. Both these 

 exceptional modes of transferring the sperm are met with in 

 the crayfishes and lobsters. 



As far as known in all the crayfishes of the world, except 

 those of North America east of the Rocky Mountains, the male 

 deposits the sperm on the outside of the shell of the female, and 

 not in any receptacle. But in the above crayfishes of the 

 central and eastern parts of North America the sperm is de- 

 posited in special receptacles in the shells of the females, and 

 the same is true for the American lobster. 



Before describing the sperm-receptacle in a Cuban and a 

 Mexican crayfish in which it was necessary to find it in order 

 to prove its general occurrence in all members of the genus 

 Cambarus, we will make a comparison of the receptacles in 

 the crayfish and lobster. 



In both animals there is but one receptacle on each female 

 and this lies on the under side of the body, between the fourth 

 and the fifth pairs of legs. 



The under side of the shell of the thorax of these animals 



may be thought of as made of more or less fused plates, one 



on each side and one on the middle of each somite. In the 



somites of the first, second and third legs the imagined plates 



Proc. Wash. Acad. Sci., August, 1908 167. 



