144 ZOOPHYTES. 



from the convexities by which these are distinguished. They are some- 

 what ventricose, swelling downwards from a narrower circular orifice, 

 whereon none of the teeth specified by Lamouroux have been seen, 

 though several are on the orifice of the vesicles. 



The cell is occupied by a hydra with about 24 or 26 deeply muricate 

 tentacula, which expand about a line between the opposite tips. It is large 

 in proportion to the cell, whence it protrudes by a long neck or body, and 

 retreats completely within the cavity. Of all the hydraoid zoophytes, it 

 may be rated the next in size to that of the Tubularia larynx. But the 

 dimensions, vigour, and aspect of these creatures are extremely dependent 

 on the salubrity of their element, and the peculiar state of the atmo- 

 sphere. 



The whole product is of a green colour, of various shades and inten- 

 sity, which is derived from the pith, as the fistulous inorganic parts are trans- 

 parent. In earlier stages the green is vivid. The stem of adults, or older 

 specimens, is occasionally yellowish or brown. I have never observed the 

 hydrse of any other colour than green, of different intensity. 



The meagre appearance of the Sertularia is remarkable. Few speci- 

 mens are equally luxuriant as the scantily clothed figures here represented, 

 Plate XXII. fig. 1 ; the same enlarged, fig. 2 ; and most of the branches 

 are frequently on one side, fig. 3. A stem has sometimes occurred, which, 

 without having generated any branches, had above 30 alternate cells. One 

 with 29 was 15 lines high, whence their dimensions and intervals may be 

 computed. A large bough had 35 on each side, these being the most nu- 

 merous ever observed. 



The food of the smaller compound zoophytes is problematical ; but it 

 is obvious that all must have subsistence to sustain life, and promote en- 

 largement. I was induced by the size of the hydra here to attempt feed- 

 ing them with soft particles of the mussel, a substance the most grateful 

 of any to most of the lower carnivorous tribes ; and I believe that I suc- 

 ceeded. I thought the particles might be discovered in the remoter parts 

 of the stomach, whither they were transmitted by a distinct channel. 

 There the contents appeared as a dark internal mass, becoming ovoidal. 



