XI 



PHYLUM ARTHROPODA 



543 



broader than that of the male : the first and second pleopods of 

 the male are modified into tubular or rather spout-like copulatory 

 organs (Fig. 439, 9} ; and the reproductive aperture is situated in 

 the male on the proximal podomere of the fifth leg, in the female 

 on that of the third. 



The testis (Fig. 449, B, t, u} lies in the thorax, just beneath the 

 floor of the pericardia! sinus, and consists of paired anterior lobes 

 (t) and an unpaired posterior lobe (u). From each side goes off a 

 convoluted vas deferens (vd), which opens on the proximal segment 

 of the last leg. The sperms are curious amoeboid bodies produced 

 into a number of stiff processes or pseudopodia (Fig. 23, /) : they 

 are aggregated into vermicelli-like spermatophores by a secretion 

 of the vas deferens. 



The ovary (A, ov, u} is also a three-lobed body, and is similarly 

 situated to the testis : from each side proceeds a thin-walled 



t 



FIG. 449. Reproductive organs of Astacus fluviatilis. A, female ; B, male. ml. ovidu<;t ; 

 oe, its external opening ; ov. ovary ; t. testis ; u, unpaired posterior portion of gonad ; vd. vas 

 deferens. (From Lang's Comparative Anatomy, after Huxley.) 



nn'ducL (od), which passes downwards, without convolutions, to 

 open on the proximal segment of the third or antepenultimate 

 leg. The eggs are of considerable size and are centrolecithal. 



As in Apus, both ovary and testis are hollow organs, discharging 

 their products internally. The ova, when laid, are fastened to the 

 setee on the pleopods of the female by the sticky secretion of glands 

 occurring both on those appendages and on the segments them- 

 selves : they are fertilised immediately after laying, the male 

 depositing spermatophores on the ventral surface of the female's 

 body just before oviposition. 



