m 



HANDBOOK OF INVERTEBRATE ZOOLOGY. 



The madreporic body is very conspicuous and its edges 

 are sharply defined. The margin of the periproct is formed 

 by seven plates, the five ovarian and two of the occular 

 plates, and the perforations through the occular plate are 

 much larger than they are in Arbacia, and there is only 

 one in each plate instead of two.) 



Fig. 36. 

 Fig. 36. — The ab-oral surface of the corona of Arbacia punctulata, a 

 little enlarged. (Drawn from natui'e by Mr. H. J, Rice, under the author's 

 direction. ) 



a. Anal plates. b. Ovarian plates. c. Occular plates, d. Inter- 

 ambulacral sutures, e. Tubercles on ambulacral plates. /. Ambulacral 

 sutures, g. Ambulacral pores, h. Tubercles on inter-ambulacral plates. 

 1, 2, 3, 4, 5. The five rays. 



