Royal Physical Society. 453 



and others, in addition to the common swimming organ, each 

 ovary is associated with a minute rudimentary umbrella, as in 

 fig. 9. In Diphyes, again, the ovary (fig. 10), furnished with a 

 large umbrella, a serviceable swimming apparatus, becomes 

 freed from the polypary, and floats away as a locomotive re- 

 productive organ, like the Hectocotylus of the Cephalopod. 

 So, also, the fixed false medusoid of C. dichotoma is nothing 

 more than an ovary with an umbrella, which last, however, 

 exercises — not the function of a swimming organ, but rather, 

 as does the gelatinous envelop secreted by the ovarian sacs of 

 Sertularia pumila, Laomedea lacerata, &c. (see p. 113) — that 

 of a marsupium. 



"We have another instance of an umbrella-shaped sac being 

 employed as a marsupial chamber in the reproductive cell of 



Sertularia fallaoc. 



In this zoophyte (as I described to the Society, April 1857) 

 the summit of the ovary puts forth four thick lobes, consisting 

 of endoderm and ectoderm covered by corallum ; these are gra- 

 dually developed (as shown in Plate XXIII., figs. 11, 12, and 13) 

 until they form an umbrella with four or eight canals (as in 

 fig. 14). The ova, after leaving the ovary, are received into the 

 cavity of the umbrella, which, on their attaining a more ma- 

 ture stage, opens at the top, and allows them free exit. 



On the Reproductive organs of Laomedea geniculata. 



Plate XXIII. 



Fig. 15. Medusoid of Laomedea geniculata — a, ovaries. 



On a former occasion I described the existence of ovaries 

 and ova in the lateral canals of Campanularia Johnstoni, and 

 the production of the young zoophytes. On examining, in like 

 manner, the medusoids of L. geniculata, immediately after 

 their exit from the capsule, I discovered their ovaries with the 

 contained ova. In some of the medusoids the ovaries were 

 situated in close proximity to the peduncle, in others, midway 

 between the peduncle and the marginal canal (as at fig. 15). 



