fi 
Bs 
> 
=a 
Ce 
Fic. 139.—Dissection of Holothurian (Holothuria tubulosa) from 
the ventral surface. 
#., Tentacles surrounding the mouth; 44, scattered tube-feet of 
ventral surface ; ¢., calcareous ring surrounding the food canal ; 
a., ampulle of tentacles (modified tube-feet); ~., circular vessel 
surrounding the gullet, giving off the branched stone canal (s#.), 
the single Polian vesicle (o.), and the five radial canals (7c.), 
which run forwards, pass through the calcareous ring, and then 
curve outwards to run on the surface of the longitudinal 
muscles (¢.7.) along the radial areas. Of the five longitudinal 
muscles, one only is marked. gl., The gut cut through at the 
beginning of the first loop; 2., the mesentery which attaches 
the gut to the body wall, showing the course of the gut; g2., 
the other end of the gut ; c/., the cloaca bound down by muscles ; 
an., the anus ; 7.4., the right respiratory tree—the left is cut short 
mle to its origin; ov., the ovary. The blood vessels are not 
shown. 
