PHYLUM ARTHROPODA 



229 



similarly situated to the 

 thin- walled oviduct (od), 

 convolutions, to open on 

 or antepenultimate leg. 

 The ova, when laid, 

 pleopods of the female 

 occurring both on those 



testis ; from each side proceeds a 

 which passes downwards, without 

 the proximal segment of the third 

 The eggs are of considerable size, 

 are fastened to the setse on the 

 by the sticky secretion of glands 

 appendages and on the segments 



B A4fct 



Fig. 130. — Reproductive organs of Astacus fluviatilis. A, female; B, male; od, 

 oviduct; oe, external opening of the same; ov, ovary; t, testis; it, unpaired 

 posterior portion of gonad ; Z'd, vas deferens. (From Lang's Comparative 

 Anatomy, after Huxley.) 



themselves ; they are fertilised immediately after laying, the 

 male depositing spermatophores on the ventral surface of 

 the female's body just before oviposition. 



The lobsters, shrimps, prawns, crabs, and hermit-crabs 

 all resemble the crayfish in the number and disposition of 

 the segments, the presence of a carapace covering both 

 head and thorax, the general structure and arrangement of 



