148 THE MEDUSAE. 



especially when such grouping runs exactly counter to previous classifica- 

 tion based upon another single character (in this case the branching of the 

 radial canals). Nevertheless, I believe that the condition of the marginal 

 organs is of greater taxonomic value than that of the canals, and that 

 Browne's (: 07) revision therefore marks a decided advance over previous 

 schemes. It must be noted, however, — and this is a point of some im- 

 portance, — that if we adopt the presence or absence of cordyli as a 

 character of prime importance, the two resultant groups show parallel 

 series, each falling into two divisions, the one with simple and the other 

 with branched canals ; while, on the other hand, if we were to retain 

 the classification based on the condition of the canals, whether branched 

 or simple, similar parallel series with reference to the presence or absence 

 of cordyli would result. Those members of the old family Thaumantidae 

 which remain after the removal of the genera with cordyli stand in need 

 of further revision. 



The genera of Leptomedusae with otocysts show their family relations 

 much more clearly than do those without such organs, it being now very 

 generally agreed that they represent two families, Eucopidae and Aequo- 

 ridae, though the position of one or two genera, whether in one or the 

 other, has been a subject of discussion. Thei-e is little doubt that these 

 two families are much more intimately related to each other than is either 

 of them to any of those members of the order which lack otocysts. 



No representatives of the genera with neither cordyli nor otocysts, nor 

 of those with branched canals, are contained in the collection ; and there 

 is only one genus of Laodiceidae, Ptychogena. Eucopidae and Aequoridae, 

 on the other hand, are well represented. 



Laodiceidae L. Agassiz, 1862. 



sens. em. Browne (: 07). 



Leptomedusae without otocysts, but with cordyli on the margin of the 

 bell. 



For generic definitions of the members of this family we may well 

 follow Browne (:07), especially since his revision, though resulting in the 

 suppression of several species, has not necessitated a general transfer of the 

 well-known members of the family. According to Browne six genera of 

 Laodiceidae are recognizable : — Laodice, with four radial canals, central 



