44 2 FERXANDUS PAYNE. 



the Hydromedusae. When these are completed we shall be in a 

 better position to make a new classification. 



Another structure to be reckoned with in a new classification 

 is the presence of an ocellus-like organ in Craspedacusta. It lies 

 at the junction of the outer margin of the bell and velar ectoderm 

 and near the nerve cord. This sense organ (probably tactile in 

 function) is ectodermal in origin (see Payne, '24). 



In connection with the taxonomic discussion of Craspedacusta 

 it is of interest to note that Joseph ('25) has been able to complete 

 the life history of Gonionemus. He followed the development of 

 the egg into the hydroid and also the formation of hydroid and 

 medusa-buds from the hydroid. The hydroid does not trans- 

 form, as Perkins ('03) was inclined to believe, into the medusa. 

 The life history is essentially the same as that of Craspedacusta. 

 Here is a form which has always been placed with the Trachy- 

 medusee. It is quite evident that it does not belong there. 

 Such studies emphasize the need of life-history work before we 

 can hope to make a permanent classification of the Hydromedusae. 



LITERATURE CITED. 

 Allman, G. J. 



'80 On Limnocodium victoria, a New Hydroid Medusa of Fresh Water. Journ. 

 Linn. Soc., Vol. 15. 



Douglas, Robert. 



'12 Zur Frage der systematischen Stellung von Limnocodium soiverbii. Zeit. 

 wiss. Zool., Bd. 102. 



Carman, H. 



'16 The Sudden Appearance of Great Numbers of Fresh-water Medusae in a 



Kentucky Creek. Science, Vol. 44. 

 '24 The Fresh-water Jelly-fish in Kentucky Again. Science, Vol. 60, p. 477, 



Giinther, R. T. 



'94 Some Further Contributions to Our Knowledge of the Minute Anatomy of 

 Limnocodium. Quart. Journ. Micr. Sci., Vol. 35. 



Joseph, H. 



'25 Zur Morphologic und Entwickelungsgeschichte von Haleremita und 

 Gonionemus. Ein Beitrag zur systematischen Beurteilung der Trachy- 

 medusen. Zeitsch. fur Wiss. Zool., Bd. 125. 



Lankester, E. Ray. 



'80 On Limnocodium sowerbii, a New Trachymedusa Inhabiting Fresh W r ater. 



Quart. Journ. Micro. Sci., Vol. 20. 

 Mayer, A. G. 



'10 Medusae of the \Vorld. Carnegie Inst. of Washington, Publication No. 

 109, Vols. I, 2, and 3. 



