70 THE VITAL FUNCTIONS. 



extremity of this pedicle, a single aperture, which 

 is the beginning of a tube leading into a large 

 central cavity in the interior of the body, and which 

 may therefore be regarded as the mouth of the 

 animal ; but in those species which have no pedicle, 

 as the Equorea, the mouth is situated at the centre 

 of the under surface. The aperture is of sufficient 

 width to admit of the entrance of prey of consider- 

 able size, as appears from the circumstance that 

 fishes, of some inches in length, are occasionally 

 found entire in the stomachs of those medusas 

 which have a single mouth. The central cavity, 

 which is the stomach of the animal, does not appear 

 to possess any proper coats, but to be formed simply 

 by a separation of the soft structure of the body. 

 Its form varies in different species; having gene- 

 rally, however, more or less of a star-like shape, 

 composed of four curved rays, which might almost 

 be considered as constituting four stomachs, joined 

 at a common centre. Such, indeed, is the actual 

 structure in the Medusa anrita, in which Gaede 

 found the stomach to consist of four spherical sacs, 

 completely separated by partitions. These arched 

 cavities, or sacs, taper as they radiate towards the 

 circumference, and are continued into a canal, from 

 which a great number of other canals proceed ; 

 generally at first by successive bifurcations of the 

 larger trunks, but afterwards branching off more 

 irregularly, and again uniting by lateral communi- 

 cations, so as to compose a complicated network of 

 vessels. These ramifications at length unite to form 

 an annular vessel, which encircles the margin of 

 the disk. It appears also, from the observations of 

 Gaede, that a further communication is established 



