HYDEOZOA. 121 



Hydra, is not permanently attached. Round the 

 distal margin of the cup arise a number of short 

 tentacles which, in Lucernaria itself, are disposed 

 in eight or nine tufts, but in Gavduella form one 

 continuous series. Their free extremities appear 

 Bucker-like or capitate ; in Depastrum, however, 

 they are simply clavate. The whole organism is 

 semi-transparent, variously coloured, and of a 

 gelatinous consistence {Jig. 25). 



The cup, in Carduella, presents at its centre 

 a four-lobed mouth, which is easily seen to form 

 tlie free extremity of a distinct polypite, occu- 

 pying the axis of the entire hydrosoma. The 

 oral margin of this polypite is simple and slightly 

 everted. Its gastric region exhibits a number of 

 tubular filaments, arranged in vertical rows, and 

 projecting freely into the digestive cavity. In 

 transverse section the pol3rpite may be described as 

 somewhat quadrilateral, with a sinuous outline, 

 which expands at its four angles to form as many 

 deep longitudinal folds, within which the simple 

 generative bands are lodged. The space between 

 the polypite-wall and the inner surface of the cup 

 is divided in the following manner. From each pro- 

 jecting angle of the gastric region run a pair of ver- 

 tical septa, which diverge widely from one another 

 so as to reach the wall of the cup at points precisely 

 opposite the two sinuosities on either side of the 

 generative band. Thus four of the equidistant 

 lines along the inner surface of the cup receive 

 two converging septa, each, however, belonging to a 

 different pair. These last septa, with the polypite 

 wall, serve to enclose four wide longitudinal 

 canals, outside of which are four other spaces, 

 bounded, within, by two septa of the same pair. 



