496 THE ANATOilY OF LWERTEBRATED ANIMALS. 



pores on the genital plates, through which their products are 

 extruded. Hoffmann has fcund the peritoneal fluid of the 

 raales full of spermatozoa. 



Pig. 145.— Development of an Echinid. (After MuHer.)— A, Echinopjedium of Kchi- 

 nil s pulchellus in the gastrula ptaye. B, fully-developed Echinopaedium {Pluteiis) 

 of tlie same species: a, mouth; &,' stomach and intestine; c.anus; ^jp^, proceseegi 

 of the body into which prolonj^ations of the internal skeleton extend. C, the 

 Echinopjedium 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 ; a', pullet; b. stomach; 6', intestine; c, radimentary Echino- 

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

 the processes of the body. 



In the JEchiiiidea, as in the Ophiuridea^ the Echinopje- 



