FIG. i2i-. Dissection of Holothurian (Holothuria titbulosa] from 



the ventral surface. 



i'., Tentacles surrounding the mouth; t.f., scattered tube-feet of 

 ventral surface ; c. , calcareous ring surrounding the food canal ; 

 a. , ampullie of tentacles (modified tube-feet) ; r., circular vessel 

 surrounding the gullet, giving off the branched stone canal (st.), 

 the single Polian vesicle (0.), and the live radial canals (;.<:.), 

 which run forwards, pass through the calcareous ring, and then 

 curve outwards to run on the surface of the longitudinal 

 muscles (/.;;/.) along the radial areas. Of the five longitudinal 

 muscles, one only is marked. ^ 1 ., The gut cut through at the 

 beginning of the first loop ; ;;/., the mesentery which attaches 

 the gut to the body wall, showing the course of the gut ; g-"., 

 the other end of the gut ; c/., the cloaca bound down by muscles ; 

 an., the anus ; r.t., the right respiratory tree, the left is cut short 

 close to its origin; 0r'.,the ovary. The blood vessels are not 

 shown. 



17 



