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. 



Fig. 145.— Development of an Echinid. (After Mfiller.)— A, Echinopsedium of FcM- 

 vuii imkhellvs'iu the gastrula >^taire. B, fnlly-developed Ecliinopaediuni (Plutevs) 

 of tlie sanifi species: a. mouth; 6, stomach and intestine; c. anus; .4 i^, processes 

 of fhe body into whii-h prolon2;atioiis of the internal siceleton extend. C, tlie 

 Echinopaj'iinm of an Echinid in which the Echinoderm is so far advanced that 

 the spines, pedicels, and pedicellariaj are visible. D, Echinoptedium of Echinus 

 Hriduft: a, mouth ; a', gullet; 6. stomach; 6', intestine; c. rudimentary Echino- 

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

 the processes of the body. 



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



