LESSON 32.] NUTRITION IN THE ECHINODERMA. 113 



538. The oesophagus passes through this circle, and opens into 

 a more or less muscular stomach, from which an intestine, often very 

 complicated, proceeds to the posterior portion of the body, where 

 it dilates into a cloaca, from which two long ramified tubes (the 

 respiratory organs) originate. These facts are demonstrated in the 

 annexed figure of Holoihuria elegans (Fig. 191). 



The mouth is shown at a / the tentacles, in this instance retract- 



FIG. 191. 



Holothnria elegans. 



ed, at b ; the stomach is seen at d ; a biliary follicle (or, what is more 

 likely, the ampulla Poliana, a bottle), which would seem to be pecu- 

 liar to this species at c ; the very long, convoluted intestine is con- 

 tinued from the stomach, and designated by the same letter d, d, d, 

 8 



