90 ZOOPHYTES. 



hydra, standing vertically around it. The margin of the body, spreading 

 somewhat beyond their origin, is rather of vascular appearance. A 

 smooth uninterrupted surface forms the under surface or sole. Fine 

 translucent green colours the whole product. — Plate XXVII. fig. 1. 



The numerous hydrse, constituting the border of this compound 

 zoophyte in activity, are sunk amidst the common mass or polyparium 

 while quiescent, in like manner as the hydrse of the Flustra hispida, the 

 Alcyoninm, or Lobularia. When induced to return, each rises separately, 

 protruding its cylindrical body a line above the surface of the back, 

 crowned by a head of crescent, or lunate shape, which is environed by 

 about 100 tentacula, as a fringe or border. These organs, in themselves, 

 curve frequently, and strike vehemently in all directions. Possibly they 

 are hollow ; but the entire hydra is of small dimensions, as this head, or 

 higher extremity, might be circumscribed by a circle not exceeding a line 

 in diameter. — Plate XXVIII. figs. 1, 2. The mouth, with a projecting 

 lip, resembles a shallow cup in the surface of the crescent. It dilates for 

 reception of the food, which is transmitted to the stomach ; from whence 

 the intestine descends below, then to return upwards, as in the ascidian race, 

 and terminates by the extremity of the intestinal canal under the orifice 

 of the mouth. — Fig. 2, a. The intestine is about a fifth of the diameter 

 of the body, which, through its thin integument, seems replete with water. 

 A peculiar motion, belonging either to the intestine, or to a neighbouring 

 vessel, is occasionally visible. 



Meantime that the parts are displayed, buoyant particles are at- 

 tracted and repelled, or received by the mouth, from the influence, it may 

 be concluded, of cilia ; or, when rejected, they are tossed about among the 

 tentacula, or from one to another, or amidst the multitude of hydrse. 

 Nevertheless, whether owing to colour, tenuity, defective light, or posi- 

 tion, I have been unable to detect the presence of cilia, though no asci- 

 dian hydra is, in as far as I know, without them. 



Here the hydrse shew great vivacity ; they are evidently endowed 

 with acute sensation. The tentacula clasp across, like the fingers of both 

 hands closing, while each of the whole also exercises a percussive faculty ; 

 and the entire creature sinks suddenly for shelter amidst the common 

 border, whereof it forms a part. 



