230 Proceedings of the 



7. The Ovisacs of the female of this zoophyte, of which fig. 

 5 shows a section of five in situ, are found to consist of ecto- 

 derm (a), muscular coat, and endoderm (c), and their nutri- 

 tive cavity is continuous with that of the pedicle, which, again, 

 is a diverticulum of the alimentary canal of the polyp. In 

 each of the ovisacs at an early period, one, or more generally, 

 two transparent ova appear, consisting of a vitellus and ger- 

 minal vesicle, inclosed in an envelope, and situated in the ge- 

 nerative cavity (ac), between the endoderm and the other coats, 

 as in the ovisac of Hydractinia. In the reproductive capsule of 

 Coryne glandulosa (Dalyell) the secretion, if I may so call it, 

 of the ova, from the outer surface of the endoderm (as shown 

 in fig. 7), is a fact beyond doubt, but in Hydractinia and 

 Clava their appearance takes place at so early a period of the 

 development of the ovisac, that the seat of their origin can 

 only be inferred from observations in other zoophytes. The 

 ova, after becoming opaque and almost black by the granulation 

 of the yoke, gradually assume a transparent pink tint, and are 

 developed into ciliated planarioid larvae, which are discharged 

 from the distal extremity of the ovisac, and after gliding over 

 the bottom of the vessel in which they are contained for a few 

 days, become fixed, and changed into minute polyps. In this 

 zoophyte the reproductive process diifers from that I have 

 described in Hydractinia, inasmuch as the young arrive at 

 their larval or planarioid stage of development before leaving 

 the ovisac, and the endodermic layer of the ovisac is gradually 

 withdrawn into the pedicle, while in Hydractinia the con- 

 tents of the ovary are discharged as ova, and the endodermic 

 layer occupies the interior of the ovary to the last, although 

 reduced in volume by absorption. 



8. The Spermsacs of the male Clava resemble the reproduc- 

 tive capsules of the female in external appearance and ar- 

 rangement. The development of spermatozoa in their interior 

 is similar to that I have described as occurring in Hydrac- 

 tinia. We have the same secretion of gelatinous matter from 

 the external surface of the endoderm ; the same development 

 in this matter of minute cells, and the production from these 

 cells of spermatozoa. But while, in Hydractinia, the endo- 

 derm of the spermatic capsule is reduced, towards the last 



