NOTES. 351 



the extremities of the posterior pair are inclosed in the groove of the 

 anterior pair ; and the end of the vas deferens becoming everted and 

 prominent, the seminal matter is poured out, and runs slowly along the 

 groove of the anterior appendage to its destination, where it hardens and 

 assumes a vermicular aspect. The filaments of which it is composed are, 

 in fact, tubular spermatophores, and consist of a tough case or sheath 

 filled with seminal matter. The spoon-shaped extremity of the second 

 abdominal appendage, working backwards and forwards in the groove 

 of the anterior appendage, clears the seminal matter out of it, and 

 prevents it from becoming choked. 



After an interval which varies from ten to forty-five days, oviposition 

 takes place. The female, resting on her back, bends the end of the 

 abdomen forward over the hinder thoracic sterna, so that a chamber is 

 formed into which the oviducts open. The eggs are passed into the 

 chamber by one operation, usually during the night, and are plunged 

 into a viscous greyish mucus with which it is filled. The spermatozoa 

 pass out of the vermicular spermatophores, and mix with this fluid, in 

 which the peculiarity of their form renders them readily recognisable. 

 The spermatozoa are thus brought into close relation with the ova, but 

 what actuallj' becomes of them is unknown. 



The origin of the viscous matter which fills the abdominal chamber 

 when the eggs are deposited in it, and the manner in which these become 

 tised to the abdominal limbs is discussed by LerebouUet ("Eecherches 

 sur le mode de fixation des oeufs aux faux pattes abdominaux dans Ics 

 Ecrevisses." Annales des Sciences Naturelles, 4e Ee. T. XIV. 1860), 

 and by Braun (Aibeiten aus dem Zoologisch-Zootomischen Institut in 

 Wurzburg, II.). 



Note VI., Chapter I., p. 42. 

 ATTACHMENT OF THE YOUNG CRAYFISH TO THE MOTHER. 



I observe that I had overlooked a passage in the Report on the 

 award of the Prix Montyon for 1872, Comptes Rendus, LXXV. p. 1341, 

 in which M. Chantran is stated to have ascertained that the young 

 crayfishes fix themselves " en saisissant avec un de leurs pinces le 

 filament qui suspend I'oeuf a une fausse patte de la m6re." 



In the paper already cited from the Comptes Rendus for 1870, M. Chan- 

 tran states that the young remain attached to the mother during ten days 

 after hatching, that is to say, up to the first moiilt. Detached before 

 this period, they die ; but after the first moult, they sometimes leave the 



