LESSON 32.] NUTRITION IN THE ECHINODERMA. 



117 



FIG. 195. 



FIG. 196. 



" as follicles," and add that " they pour their secretion into the respi- 

 ratory organs." * 



SIPUNCULUS. 



548. The rough Syrinx, Tube-worm, or Sipunculus, according 

 to modern classification, is a very curious animal, and as much (ap- 

 parently) unlike a Star-fish as can be imagined. It is, however, 

 closely allied to Holothuria. 



549. The body is cylindrical, and covered with a strong coriaceous 

 (leathery) integument, generally rugous (wrinkled), except at the 

 posterior extremity, which is longitudinally grooved to its termi- 

 nation. A specimen, about two inches long, is represented in Fig. 

 195. On opening a simi- 



ilar specimen, a very cu- 

 rious condition of the 

 nutrimental apparatus 

 presented itself; the gas- 

 tric cavity (Fig. 196, a), 

 is clearly distinguish- 

 able 5 this terminates in 

 an intestine (b) apparent- 

 ly filled with fine sand, 

 which is of considerable 

 length. It descends in 

 a tortuous course to the 

 posterior portion of the 

 body; it then winds upon 

 itself in a series of close 

 folds, and terminates by 

 a small tube (c) at the 

 vent, which is situate 

 near the base of the proboscis (the latter not exceeding one-tenth of 

 the body in length), close to the anterior extremity. The longitu- 

 dinal muscles are beautifully displayed, and several strong tendons, 

 some oblique in their position, are equally well shown. Two long, 

 narrow, sacculated bodies (d, d) are seen, but whether they are 

 glandular, or Ampullae (like a bottle ; the heart of Holothuria is 



* In the year 1841, the author had thirteen living specimens of C. frondosa, in his posses- 

 sion in Edinburgh. After a variety of interesting experiments with the living animals, he 

 displayed their anatomy in a series of preparations now in the Hunterian Museum. Draw- 

 ings of them, of natural size, he possesses. 



Sipunculus. 



Nutrimental organs, Sipunculus. 



