256 Proceedings of the 



off at the same time, and after living a few days, became 

 affected with the convulsive attacks so feelingly described by 

 Professor Edward Forbes, to which infant Acalephs are so 

 prone, and died in contortions shocking to see. 



[Since the foregoing observations were communicated to the 

 Royal Physical Society, I have several times obtained L. 

 acuminata, and it is now growing in great luxuriance in my 

 tanks. One of the specimens covers a space of 4 by 8 inches 

 on the surface of the glass, with a net- work of creeping fibres, 

 from which polyp-stems spring at very regular intervals of 

 about a tenth of an inch. The polyp-stems of this specimen 

 bear each a single polyp only. In other specimens which are 

 seated on univalve shells, and cannot therefore so readily spread 

 themselves, the polyp-stems become repeatedly branched. 

 In these cases the single polyp-stem gives off one, two, or three 

 branches beneath its cell ; these branches in like manner 

 originate others, until the polyp-stem becomes transformed 

 into a more or less bushy shrub, covered with polyps (Plate 

 XIII., fig. 2), and rarely bearing a large medusa-bud, which 

 is generally developed from the first stem. 



The medusa-bearing stem (Plate XIV., fig. 2) at an early stage 

 resembles one of the ordinary polyps (Plate XIII., fig. 1, 6), in 

 an imperfect state of development, having the same transparent 

 globular summit, in which, as well as in the stem, an active 

 circulation of granules may be detected. It may be considered 

 as a reproductive branch or polyp. The medusoid b buds forth 

 from beneath the enlarged head, and is inclosed in a sac c form- 

 ed from the ectoderm of the polyp. As the medusoid grows, 

 first the head, and afterwards the body, of the reproductive 

 polyp a is absorbed, and the sac of the ectoderm is afterwards 

 ruptured by the vigorous flapping of its inmate. Absorption 

 of the connection between the stem and the medusoid then 

 takes place, and the latter is freed in about six or eight hours 

 afterwards. 



The striae of the empty polyp-cells appear to be due to a 

 folded state of the membrane, as they disappear when the cells 

 are fully distended by their inmates. — Dec. 3, 1857.] 



