108 DISCOPHOR^. Part III. 



elongating, as if raised or dropped, almost independently of the parts with which 

 they are, nevertheless, continuous. At times, however, the whole mass of the acti- 

 nostome is raised in a bulk, and brought nearer to the disk. When at rest, floating 

 near the surface of the water, the gentle contractions of the margin of the disk 

 alone maintaining the animal in its position, the pillai's of the actinostome are 

 more elongated than at other times, as is the case in PI. III., and the folds of 

 the curtains are gathered up in large rounded masses. When moving actively, 

 however, they are more stretched, sometimes to a length exceeding several times 

 that which they exhibit in PI. III. 



It is very difficult to keep large specimens of this species alive, in confinement, 

 for protracted observation. It is evident that these animals require a very large 

 supply of the purest water, since they rapidly decompose, in a very short time, 

 when kept in a limited quantity of Avater. A few hours after they have been con- 

 fined in glass cylinders, even sufficiently large to allow them to stretch their tenta- 

 cles to a greater extent than is exhibited in PL III., and wide enough to hold 

 them without touching the sides, the tentacles begin to drop off, one after the 

 other, and the marginal folds of the actinostome to decompose ; and no care, not 

 even the frequent changing of the water, can keep them alive beyond twenty-four 

 hours. They soon discolor the water, and their Avhole mass becomes soft and offen- 

 sive. I have, however, observed a very singular phenomenon in a specimen which 

 I had placed in fresh sea-water, after removing all the tentacles, the genital pouches, 

 and the actinostome, and leaving only the gelatinous disk and the horizontal part 

 of the lower floor. The specimen remained alive for many days ; from which I 

 infer that it is chiefly the most active parts of the body, hanging from the lower 

 floor, which require the largest supply of fresh, aerated sea-water. A specimen 

 which I had divided into halves, and a segment representing about one fourth of 

 the whole disk, to which fragments of the lower floor remained attached, but from 

 which all the tentacles, and the genital pouches, with the actinostome, had been 

 removed, continued to live and contract and move about, in a large tub, during 

 a fortnight. Such a persistence of life, in portions of the animal, contrasts strangely 

 with the rapidity with which entire S2>ecimens decay and die in confinement, and 

 can only be explained by the more delicate nature of the parts hanging from the 

 lower floor, when compared to the tougher texture of the horizontal part of that 

 floor, and the peeuliar consistency of the disk. 



