312 



THE STARFISH 



cardiac communicates with the small pyloric division 

 (Fig. 77, pyl. st\ which also gives off five pouches, the 

 pyloric coeca (Fig. 76 and ']T,pyl. cce); but each of these, 

 instead of extending merely into the base of the correspond- 

 ing arm, divides into two, and both branches extend to the 

 extremity of the arm, giving off as they go small side- 

 branches, so that the whole csecum has a tufted or sacculated 

 character. The pyloric caeca are lined by gland-cells, and 

 in them the digestion of the food takes place. They are 

 connected with the dorsal walls of the arms by mesenteries 

 (Fig. 76, B, mes). 



The pyloric division of the stomach leads into a very 

 short intestine which passes upwards in a straight line to the 

 anus {an), previously giving off two intestinal caeca {int. cos) 

 situated inter-radially — not radially like the blind offshoots 

 of both divisions of the stomach. 



The whole enteric canal is lined with enteric epithelium 

 (Fig. 76, Ent. Epthm), and is covered by the visceral layer 

 of caelomic epithelium {Ccel. Epthm) : it has no muscular 

 layer. There is a spacious coelome (Cfl?/) between the body- 

 wall and the enteric canal filled with a watery fluid contain- 

 ing leucocytes. The coelomic epithelium is ciliated, the 

 cilia effecting a circulation of the coelomic fluid. The 

 dermal gills {Resp. ex), already referred to, communicate 

 with the ccelome, and are, in fact, hollow outpushings of 

 the body-wall. They serve to bring the ccelomic fluid into 

 close relation with the surrounding water, and are therefore 

 to be looked upon as organs of respiration. 



One of the most characteristic structures in the anatomy 

 of the starfish is a peculiar system of vessels called the 

 water-vasadar or atnbulacral system : it is of great func 

 tional importance, being connected with the working of the 

 tube-feet. 



