Pjq^ 157. Dissection of Holothurian {Holothuria tuhulosa) from 



the ventral surface. 



t Tentacles surrounding the mouth; tj., scattered tube-feet of 

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

 a ampullae of tentacles (modified tube-feet) ; r., curcular vessel 

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

 the single Polian vesicle (o.), and the five radial canals (r.c), 

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

 curve outwards to run on the surface of the longitudinal muscles 

 a m ) along the radial areas. Of the five longitudinal muscles, 

 one 'only is marked, gi., The gut cut through at the teginmng 

 of the first loop ; m., the mesentery which attaches the gut to 

 the body wall, showing the course of the gut ; g2., the other end 

 of the gut • cl , the cloaca bound down by muscles ; an., the 

 anus • r.t., 'the right respiratory tree— the left is cut short dose 

 to its' origin • ov., the ovary. The blood vessels are not shown. 



