8 THÉEL, HERMAPHRODISM IN HOLOTIIURIDS. 



tion with the cavities of the rnore or less elongated and rami- 

 fied genital tubes which protrude from it. 



In young individuals measuring three or four cm. in 

 lengtb, the genital basis presents itself as a very insignificant 

 expansion at the left side of the dorsal mesentery, where the 

 efferent dnct enters it. The older the animal grows, the more 

 the genital basis increases and iinally it appears as a rather 

 considerable prominence or swelling, projecting from the left 

 side of the mesentery. 



The reproductive organ of a full grown individual bent downwards from the 

 dorsal mesentery. g efferent duct: gh genital basis: c posterior portion of the 

 genital basis devoid of tubes but provided with small imaculse» or minute pro- 

 tuberances; cl a genital tnbe .still not resorbed; ot nearly ripe ovarian tubes; 

 mt immature male tubes. Magnified. 



In an early stage of the development, the genital basis 

 is devoid of every trace of a naked portion behind that part 

 which carries the tnbular genital appendages. But, during 

 the growth of the animal, snch a portion becomes visible by 

 degrees and enlarges itself successively, forming at last a 

 .spiral or helicoid terminal-portion bent towards the dorsal 

 mesentery and terminating in an obtuse or somewhat elon- 

 gated tip. A closer inspection of it reveals that it bears on 



