308 NOTE ON THE DEVELOPMENT OF THE VERSURID^E, 



The number of marginal bodies or organs of sense (Sinneskolben) 

 is in the Discomedusse nearly always eight, only very few possess 

 more, none less. The number hardly ever exceeds 32. The develop- 

 ment of the forms with more than eight marginal bodies is 

 unknown. Haeckel (1) supposes that in these cases already the 

 Scyphystoma possesses a greater number of tentacles. 



Our Phyllorhiza, in its adult state possesses eight marginal 

 bodies, between every two of which there are two ocular flaps, four 

 simple and four double marginal flaps (plate V., fig. 4.) 



I have never observed any variation in the number of the 

 marginal bodies of the adult animal except when the margin had 

 been injured, in which case, marginal bodies are produced irregu- 

 larly in the regenerated and irregular part of the margin. The 

 young stages (plate V., figs. 1-3) possess a greater number of 

 marginal bodies. It is not likely that Phyllorhiza punctata will 

 differ in this respect from all the other members of the Family, 

 and so we may assume it as not unlikely, that the development 

 described below for Phyllorhiza punctata is met with in many of 

 the other Versuridse. 



The youngest stage which I have observed, measuring 15 mm. 

 (fig. 1) possesses 24 marginal bodies. In the radii of the first, 

 second, and fourth order. The margin of the Umbrella bears in 

 each Octant between two ocular flaps, four broad and low ^flaps 

 which are to be considered as two flaps only, each possesses an 

 indenture in the middle, the accessary marginal bodies are situated 

 in these indentures. 



These sense-oi-gans are slightly smaller than the persisting eight, 

 but do not differ from them in shape. Larvse measuring 30 mm. 

 across the Umbrella show these marginal bodies in a few Octants 

 only, whilst in the others there is situated only one sense-organ in 

 the Radius of the third order. It is evident that the larva? lose 

 these marginal bodies of the quarternary Radii at the time of 

 their attaining this size. They are slowly replaced by others, one 

 always taking the place of two. A form is in that way attained, 



(1.) E. llaeclul. Das System der Medusen. Seite 45S. 



