76 



THE VITAL FUNCTIONS. 



of a moiitli, leading to s, the stomach, of which tlic lower 

 orifice is open, and which is suspended in the general cavi- 

 ty, hv means of vertical partitions, of which the cut edges 

 are seen helow, uniting at a central point, c, and passing be- 

 tween the stomach and the integument. These muscular 

 partitions arc connected above with three rows of tentacula, 

 of which tlie points are seen at t. The ovaries (o) are seen 

 attached to the partition; and also the apertures in the lower 

 part of the stomach, by whicli they communicate with its 



cavity. 



If we considered the medusa as having four stomachs, we 

 mi'^^ht in like manner rcsrard the Jlsterias, or star-fish, as 

 having ten, or even a greater number. The mouth of this 



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radiated animal is at the centre of the under surHice; it leads 

 into a capacious bag, situated immediately above it, and 

 which is properly the stomach. From this central sac there 

 proceed ten prolongations, t)r canals, which occupy in pairs 

 the centre of each ray, or division of the body, and subdi- 

 vide into numerous minute ramifications. These canals, 

 with their branches, are exhibited at c, c. Fig. 25S, which 

 represents one of tlie rays of the Asterias, laid open from 

 the upper side. The canals are supported in their positions 

 by membranes, connecting them with the sides of the ca- 

 vity in which they are suspended. 



In the various species of Echini, we find that the ali- 

 mentary tube has attained a more perfect development; for 

 instead of constituting merely a blind pouch, it passes en- 

 tirely through tlic body of the animal. We here find an 

 oesophagus, or narrow tube, leading from the mouth to the 



