122 ZOOPHYTES. 



thickness of the smooth part, which I considered the original body of the 

 hydra, now towards a line in diameter. But it must be recollected all 

 these measurements and proportions are to be deemed only approxima- 

 tions to the truth. 



Recently, preceding March 30, two of the largest companions of 

 figs. 9, 10, — still suspended by adhesion to the side of the same vessel, — 

 were undergoing a change, the tentacula were shortening. The body re- 

 mained plump and healthy, when only the tips of the tentacula continued 

 visible at the extremity of the pendulous prolongation. — Plate XVIII. 

 tig. 11, h. This subject extended five-eighths of an inch. The pendulous 

 prolongation of its fellow, fig. 12, whose tentacula had entirely disap- 

 peared, was still more ample on the 30th of March. Its total length was 

 about five lines. 



In a week, that is on April 8, numerous other specimens in the for- 

 mer vessel which had contained figs. 13, 14, were undergoing changes 

 similar to those now described. 



Suffice it to observe, in this place, that the pendulous rolls were gra- 

 dually advancing to maturity, and progressively resolving into Medusae as 

 the former. 



It is to be remarked of the four animals whose history is thus abbre- 

 viate, Plate XVIII. figs. 9, 10 : 11, 12 ; 13, 14, 15, no other creatures 

 had been in the same vessels along with them ; nor could the strangers 

 have escaped detection if there, — the vessels being only two inches in dia- 

 meter. From the numbers in one of them, the hydrse were of all ages. 

 Although I have endeavoured to describe and represent the actual 

 appearance of the subjects, and to follow the course of incidents as accu- 

 rately as possible, there are still various points which I feel sensible of 

 having overlooked, and others which there was no opportunity of observ- 

 ing, both meriting much farther investigation. 



Certain facts admit of no dispute. Such as the existence of a vigorous 

 hydra attached to a solid substance, with long flowing silky tentacula : an 

 alteration in the figure'^of the body, or the formation of an embryonic roll 

 of Medusaj on the disc ; the gradual maturity of each Medusa, and its 

 liberation from the roll ; the disappearance of the original tentacula of the 



