Km. 371. Organisa- 

 tion of Holothuria 

 tubulosa. Tim blood 

 vascular system is 

 marked black. 1, Oral 

 tentacles ; 2, stone 

 canals ; 3, water vas- 

 cular ring ; 4, Polian 

 vesicle ; 5, gonads ; r,, 

 longitudinal musclrs ; 

 7, anterior section of 

 intestine ; S, ventral 

 intestinal vessel ; !>, 

 radial water vessel ; 10, 

 vascular anastomoses : 

 11, dorsal intestinal 

 vessel ; 12, filaments 

 and strands (of tin' 

 nature of both muscle 

 and connective tissue) 

 which attach the cloaca 

 to the body wall ; 13, 

 cloaca ; 14, cloacal 

 aperture (anus) ; 15, 

 middle section of the 

 intestine ; 10, posterior 

 section of the same ; 



17, right branch ial tree ; 



18, rete mirabile ; I'.'i, 

 radial canal of the 

 water vascular system ; 



20, left branchial tree ; 



21, tentacle ampulla 

 (after Milne Edwards 

 and Carus). 



13 



