132 



MELICERTUM CAMPANULA. 



Fig. 203 only a somewhat younger form of the same Medusa,. We 

 have thus established, by the observation of this Medusa, as well as 

 from the young Hydrarium of Melicertum and Lafoea, the probable 

 character of the Hydrarium from which Melicertum, Staurophora, and 

 those Medusas which have no marginal capsules, are developed ; show- 

 ing that they hold an intermediate position between the Campanu- 



Fig. 203. 



Fig. 204. 



Fig. 205. 



larians and the Tubularians, being more closely allied to the latter in 

 their embryonic condition, and assuming as adult Medusae somewhat the 

 aspect of Campanularian Medusas. The Trichydra pudica of Wright 

 is also closely allied to Lafoea and Staurophora. In the young Medusa 

 we have at first only two primary tentacles (Fig. 204) and two rudi- 

 mentary ones, and in the next stage there are sixteen. (Fig. 205.) 



The presence of eye-specks at the base of the tentacles of the young 

 Medusae of Lafoea calcarata and of Staurophora laciniata are the surest 

 means of distinguishing them with accuracy. The differences in the 



shape of the bell between these youngest 

 Medusae (Fig. 203) and somewhat older 

 stages (Fig. 205), are of a similar character 

 to those w r e are familiar with among the 

 young Campanularian Medusae of other gen- 

 era. To judge from analogy, I strongly sus- 

 pect that the young Medusa of Staurophora 

 will in its turn be a Medusa, similar to these 

 Lafoean forms, having at first but two primary tentacles. In the next 



Fig. '203. Profile view of very young Medusa of Melicertum campanula ; Lafoean like. See 

 Fig. 192. 



Fig. 204. Half the disk of the same, seen from the actinal pole. 



Fig. 205. Young Melicertum, -with only four completely formed chymiferous tubes. lc, first 

 set of chymiferous tubes ; 2c, second set ; 1, 2, 3, tentacles of the first, second, and third sets. 



