ON THE ANATOMY OF THE FAMILY OF THE MEDUS/E I9 



in the same position. There is, however, one discrepancy. M. 

 Edwards states that the generative lamellae ''sont tout a fait distincts 

 de la cavite digestive centrale." I think that on repeating his exami- 

 nation he would find this not to be the case. In Oceania, at any rate, 

 I could readily introduce a needle from the stomach into the canals, 

 and show that the lamellje were mere dilatations of their wall. 



In Polyxenia, where the canals are very short and the central 

 cavity very large, the ova are situated in the under wall of the cavity, 

 according to Will ; but this author enters into no particulars as to the 

 structure of the wall. 



41. The generative organs of the Phanerocarps have been much 

 investigated. The general result arrived at appears to be, that they 

 are plaited tubular bands attached to the concave wall of a depression 

 existing between the pillars of attachment of the stomachal membrane ; 

 that they are altogether separate from the central cavity ; that the 

 spermatozoa are developed in pyriform sacs opening externally, and 

 that the ova lie free in the substance of the ovarial band. 



42. The structure of the generative organs in Phacellophora is as 

 follows : — The voluminous folded and plaited stomachal membrane is 

 attached by four thick pillars to the under surface of the disc. The 

 edges of the pillars are connected by a thin membrane, which is con- 

 cave externally so as to form a sort of shallow depression or generative 

 cavity, but the central and some of the marginal parts of this mem- 

 brane are produced into long plaited processes, which hang far out of 

 the cavity, fig. 18. Each process is a sort of sac communicating freely 

 at its attached extremity with the cavity of the stomach, air, &c., 

 passing readily from the one to the other. It is in fact a sort of ever- 

 sion of the walls of the stomach, or more properly, of the central 

 cavity. It consists in its upper or attached part of nothing more than 

 the two " foundation membranes," and here they are smooth, but at 

 their lower or free edge they become much plaited, acquire a deeper 

 colour, and exhibit the characteristic generative elements. Short 

 tentacles, similar to those oi Rliizostovia {11), 2.X& scattered over the- 

 inner surface of each process, fig. 21. 



43. In the ovarium, the two membranes develope between them 

 immense multitudes of ova with a dark granulous yelk and clear 

 germinal vesicle. The ova are attached to the outer surface of the 

 inner membrane, the outer membrane passing quite freely over them, 

 fig. 24. 



44. The testis is similarly composed of two membranes with an 

 intervening space. The inner membrane is produced into a vast 

 number of thick pyriform sacs, which lie between the two membranes,, 



C 2 



