ECHINODERMATA OF NEW ENGLAND. 67 



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

 lantern. Development with pluteus. Ovaries five. 



///. Spatangoids. Body swollen, globular, elongated. 

 Ambulacra! 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. punctulata, Lam. 



STRONGYLOCENTKOTUS. 



Strong ylocentrotus. Body globose ; anus and mouth op- 

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



