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HANDBOOK OF INVERTEBRATE ZOOLOGY. 



d. Turn the periproct over, and notice : 



1. The five genital ducts, which run from the reproduc- 

 tive organs to pass through the pores of the ovarian plates 

 to open on the upper surface. 



2. The dark brown intestine (Fig. 39, tZ), opening in 

 the centre of the periproct. 



Fio. 39. 



FIG. 39. Side view of Arbacia ptmetulata, with the spines and part 

 of the corona removed, to show the internal organs. (Drawn from nature 

 by H. J. Rice, under the author's direction.) A little enlarged. 



a. Reproductive organs. d. Intestine. e. (Esophagus. /. Pyloric 

 division of stomach, g. Cardiac division of intestine. 



3. The oesophagus, e; a somewhat similar brown tube, 

 which forms a loop close to the anal end of the intestine. 



4. From this loop the oesophagus passes into the centre 

 of the upper surface of a large complicated structure, 



