642 



THE INVERTEBRATA 



—por. 



-g.plt. 



amb.-. 



Fig. 448. A diagram of an aboral view of the dried shell of an Echinus. The 

 spines, pedicellariae and tube feet have been removed. From Shipley and 

 MacBride. amb. ambulacrum; An. anus; ho. bosses which bear the spines; 

 g.plt. genital plate with genital pore ; jun. line of junction of ambulacral and 

 interambulacral plates ; mad. madreporic plate ; oc.plt. ocular plate ; por. pores 

 through which tube feet protrude ; /)/)r. periproct (leathery skin around anus). 



Fig. 449. Pedicellariae of Echinus miliaris. Enlarged, but not accurately 

 to scale. A, Trifoliate. B, Ophiocephalous. C, Thdactyle. D, Gemmiform. 



