90 THE VITAL FUNCTIONS. 



or stomach (s), situated in the upper part of the 

 cupola. The section of this oesophagus is visible 

 at the centre of Fig. 249, where its cavity has 

 the form of a cross. The stomach has a quad- 

 rangular shape, as in the ordinary medusae, and 

 from each of its four corners there proceed 

 vessels, which are continuous with its cavity, 

 and are distributed by endless ramifications over 

 the substance of the cupola, extending even to 

 the fringed margin all round its circumference. 

 The mode of their distribution, and their nume- 

 rous communications by lateral vessels, forming 

 a complete vascular net-work, is seen in Fig. 251 , 

 which represents, on a larger scale, a portion of 

 the marginal part of the disk. The two large 

 figures (249 and 252) also show the four lateral 

 cavities (r, r, Fig. 252), which are contiguous 

 to the stomach, but separated from it by mem- 

 branous partitions : these cavities have by some 

 been supposed to perform an office in the system 

 of the Medusa corresponding to respiration ; an 

 opinion, however, which is founded rather on 

 analogy than on any direct experimental evi- 

 dence. The entrances into these cavities are 

 seen open at e, in Fig. 249, and at e, e, in the 

 section Fig. 252. A transverse section of one of 

 the arms is given in Fig. 253, showing the form 

 of the absorbent tube in the centre : and a similar 

 section of the extremity of one of the tentacula 

 is seen in Fig. 254, in which, besides the central 



