SPERM TRANSFER IN CERTAIN DECAPODS. 



By E. A. Andrews, 



Of the Johns Hophins University, Baltimore. 



Among the Crustacea it is common for the sperm to emerge from 

 the males enveloped in more or less secretion from the deferent ducts. 

 Thus are formed sperm masses, which are enveloped by secreted 

 coverings; these are transferred to the females by the aid of special 

 appendages and constitute the "spermatophores." These sperma- 

 tophores are received by the females chiefly in three ways— either the 

 spermatophores are fastened merely upon the outside of the shell or 

 they are directly introduced into the oviducts, or they are phiced 

 within some special spermatheca or receptacle not used for any other 

 purpose. This latter case, the employment of a spermatheca, is 

 rare, but it is especially deserving of study and explanation. 



While the crayfish of the genus Astacus applies spermatophores 

 over the surface of the shell of the female, the crayfish of the genus 

 Camharus fills a special receptacle within wliich the sperm may lie 

 dormant for months. In the lobster there is a similar receptacle, 

 but it is a space between elevations of the shell, while the receptacle 

 in Camharus is a pit within the shell. 



A peculiar receptacle known as the "thelycum" is found in certain 

 prawns, the Peneidse. Outside these few decapods a receptacle is 

 known in the remarkable mountain shrimp of that group of primitive 

 Eumalacostraca, the Anaspidacea. 



To Dr. W. T. Caiman belongs the credit of pointing out the impor- 

 tance a comparative study of these organs may have in the proper 

 classification of the Crustacea. Any additional cases of the occur- 

 rence of such median spermatheca would be welcome, but their great 

 importance should make one very critical in asserting to their 

 reality. In his recent account of the Anaspidacea, Geofi^rey Smith 

 has described a hke receptacle in the deep-sea prawns of the group 

 Eryonidea, and asserted the fundamental nature of this spermatheca 

 as a decapod character. 



It is the object of the present paper to describe the sperm receptacle 

 in certain of the Peneidse, and further to show how very doubtful is 

 the existence of any spermatheca in the Eryonidea. 



Proceedings U. S. National Museum, Vol. 39— No. 1791. 



419 



