496 



THE ANATOMY OF INYERTEBRATED ANIMALS. 



pores on the genital plates, through which their products are 

 extruded. Hoffmann has found the peritoneal fluid of the 

 males full of spermatozoa. 



a 



Fig. 145.— Development of an Echinid. (After Mftller.)— A, Echinopaedium of Echi- 

 nus pulchellus in the gastrnla stage. B, fully-developed Echiuopsedium (Pluteus) 

 of the same species: a. mouth; b, stomach and intestine; c. anus; A F, processes 

 of the body into which prolongations of the internal skeleton extend. C, the 

 Echinopseuium of an Echinid in which the Echinoderm is so far advanced that 

 the spines, pedicels, and pedicellariae are visible. D, Echinopaedium of Echinus 

 lividus: a, mouth; «'. eullet; b. stomach; £>', intestine; c. rudimentary Echino- 

 derm; c', the ambulacral sac; c", the external opening of its duct; A A, FF, B, 

 the processes of the body. 



In the Echimdea, as in the Ophiuridea, the Echinopae- 



