21 



similar." He refers to the observations on the copulation 

 of the river crayfish [Potamohius fluviatilis) made by 

 Chantram and other naturalists, and also to Cano's 

 account of the laying of the eggs in the crab Maia. 

 References bearing indirectly on the subject are also 

 given by Herrick. 



Chantram's account of the extrusion of the eggs in the 

 river crayfish is as follows : — " When the time comes for 

 the extrusion of the eggs, the female raises herself upon 

 her feet, and then the abdominal appendages secrete for 

 a number of hours a grayish, somewhat viscous mass. 

 She thereupon lies upon her back, bends her tail towards 

 the opening of the oviducts so as to form a kind of cistern 

 or chamber, into which, during the following night, the 

 eggs are received as fast as they are expelled from the 

 genital organs. This expulsion lasts from one to several 

 hours. "t 



Cano gives the following account of the laying of the 

 eggs in the Crab Maia. " The eggs at the time of ovul- 

 ation, pass the opening of the receptaculum seminis, and 

 are here invested with a coat of cement, which is secreted 

 and held in the receptacle. The eggs .... are expelled 

 one at a time by means of the vulvular apparatus .... 

 The eggs thus ejected fall into the abdominal chamber. 

 The female beats them about with repeated blows of the 

 tail, while the pleopods, keeping them in continued 

 agitation, make them converge to the centre of the 

 abdominal pouch. The deposition of eggs is effected in 

 Maia in the course of twenty-four hours."* The position 

 of this crab during the extrusion of the eggs is not noted. 



The Eev. T. 11. R. Stebbing, in his book " A History of 

 Recent Crustacea," | gives the following reference, from 



t Bulletin of the United States Pish Commission, Vol. XV., p. 36. 

 * Op. cit., p. 49. 

 I Internat. Scientific Series, Vol. LXXIV. 



