ECHINODERMATA OF NEW ENGLAND. 



67 



of petaloid openings. Anus on edge of disk. Aristotle's 

 lantern. Development with platens. Ovaries five. 



///. 8pa tang oids. Body swollen, globular, elongated. 

 Ambiilacnil zones of different lengths, and more or less 

 modified mouth and vent asymmetrical. No Aristotle's 

 lantern. Development with pluteus. Ovaries four. 



Echinoids. 



Arbacia. Body globose ; vent and mouth opposite ; 

 two kinds of spines, the larger few in number ; color pur- 

 ple. Anus closed by four triangular plates. Pluteus with 

 two lateral anal rods. 



A. punctulala. Lam. 



STRONG YLOCENTROTUS. 



Strong ylocentrotus. Body globose ; anus and mouth op- 

 posite. Spines ot one kind, short, small, greenish color. 



