THE SPERM-RECEPTACLE IN CAMBARUS. 173 



Ortmann having shown that the genus Cambarus (Proc. 

 Wash. Acad. Sci., 1906) could be divided into six subgenera ; 

 the existence of the sperm-pocket in random members of all 

 subgenera would approximately establish its presence in all the 

 members of the genus. The annulus was found to contain a 

 sperm-pocket of the same fundamental structure (but with 

 specific differences) in species of the subgenera, Faxonius, 

 Bartonius and Cambarus (Proc. Boston Soc. Nat. Hist., 

 1906) and later the same was found true for a species of the 

 subgenus Cambarellus (Biol. Bull., 1908). 



In the present paper the annulus is described in crayfish of 

 the two remaining subgenera, Procambarus and Paracambarus, 

 and the same sperm-pocket found in all. 



Owing to the kindness of Dr. Ortmann, I have been able to 

 study the annulus in six specimens of Cambarus (Procambarus) 

 cubensis Erichs., and in one of his type specimens of Cambarus 

 (Paracambarus) -paradoxus Ortm. The former came to him 

 from the Rio Almendares, Calabazar, Prov. Habana, Cuba, 

 and the latter from the state of Puebla, Mexico, through the 

 Paris Museum. These specimens of Procambarus had so many 

 lost and regenerating limbs that this species would seem to be 

 an especially favorable one for the study of regeneration. 



In this Cuban crayfish the annulus is known from a descrip- 

 tion of Faxon (Revision Astacidae, 1885) to be " composed of a 

 larger anterior, bilobed tubercle and a smaller posterior tubercle " 

 and Ortmann found that it showed an S-shaped fissure on the 

 posterior tubercle. This fact and the figure given by Ortmann 

 left little doubt that, when looked for, a sperm-pocket would be 

 found within this annulus. However there was doubt as to 

 what should be regarded as the real annulus since Faxon gave 

 the name to all three tubercles, while Ortmann stated that it 

 seemed to him only the posterior tubercle ought to be regarded 

 as the annulus. 



The following illustrations, in the light of the above consider- 

 ations as to the morphology of the annular plate, will show that 

 although the receptacle is all within the posterior tubercle, yet 

 that alone is not the annulus, but all three tubercles together 

 form the annulus. 



