110 ZOOPHYTES. 



in greyish patches of gelatinous aspect, like the spawn of frogs, as an irre- 

 gular superficial stratum, equal to two or three square inches, often tend- 

 ing to diffuse in angular prolongations ; others resembled the specimen, 

 Plate XXX. fig. 1. All invested the branches lopped off birch, beech, 

 and different neighbouring trees, falling accidentally into the pond, which, 

 according to my information, had been drained completely three or four 

 years previously. None were found on leaves. 



The specimen, fig. 1, invested an old birchen branch as a single stra- 

 tum, with three prominences, a, b, c, rising from it, here bearing much re- 

 semblance to the form and consistence of the Alcyonium digital um or 

 lobularia of later authors. Numerous ascidian hydra? issued from the sur- 

 face, of the same general conformation as others of this kind, but consi- 

 derably larger, for the whole protruded between two and three lines, and 

 the head expanding nearly a line in a lunate form, was provided with about 

 70 tentacula. Towards 40 of these composed the exterior row ; and to- 

 wards 30 the inner row of the crescent. They were active, long, and trans- 

 parent, frequently exercising their percussive faculties. Though eluding 

 observation from various causes, especially the want of optical instruments, 

 at the time, active cilia were undoubtedly present, for along with the same 

 motions and habits, together with the attraction and repulsion of buoyant 

 particles, were their tossing about among the tentacula, as witnessed in the 

 rest of the race. Part of one of the prominences is represented, fig. 2, 

 whence the figure and proportions of the hydrse are seen. 



This animal is extremely vivacious, and displays both its form and its 

 habits in greatest perfection on the approach of night. Then, when undis- 

 turbed, and all the organs in fullest expansion, the hydra, on the slightest 

 shock or alarm, collapses and sinks down in a twinkling, and the skin 

 closes as an obtuse conic frustum over it. Now the included animal is of 

 cream colour or primrose-yellow, as seen through the skin ; and while in this 

 state, the prominence of the cell above is capable of some motion. Next, 

 the creature rises slowly and cautiously to unfold as the inverted finger of 

 a glove, then exhibiting the stomach as dark-grey and ovoidal, if replete 

 with food. Thus the integumentary skin connecting the hydra with the 

 specimen or common mass, is modified by the position of the hydra, whe- 



