80 ACALEPIIS IN CxENERAL. Part I. 



of P^ruhim, and for the young- free Medu,><a3 of the Canipanuhiriiiiis that of Tudinna- 

 buliiiii, all projiosed by Dalyell ; for the young of the Discophorie Ave may choo.se 

 between the name of Ilijdra, also proposed by Dalyell, and that of ScupMstoma} 

 used by Sars ; and for the next stage of their development we have the name 

 of Struhild, introduced Ijy Sars and generally adopted. The young free Medusa 

 may best be called Ephjra, as that name Avas first api)lied to it Avhen it was 

 considered as a distinct genus. If we retain the name Ilj'dra for the sterile animals 

 of the Hydroid type, and that of Scyphostoma for the 3'oung Medusa, the name 

 of Mi'dma would be most appropriate for all the adult Medusoids. Our termi- 

 nology Avould then be fixed in the following manner : Plamda would designate the 

 emltryonic state of the yoinig Acaleph just hatched froni the egg, and moving 

 aljout by the aid of vibratile cilia ; such planula3 are born not only from the eggs 

 of Hydroids, but also from those of Discophora^, and the joung Polyps exhibit 

 the same appearance. The name Sci/jdiosicDim would apply to the young, from the 

 time it is attached and the tentacles begin to make their appearance. In the 

 Hydroids and Polyps this condition becomes 2)ermanent, as the Avorm-like state of 

 the larva) of the higher Articulates becomes permanent in the Worms ; it is there- 

 fore apjH'Ojjriate to retain the name ILjdra to designate the advdt Scyphostoma, 

 which undergoes no further development, and that same name may equally Avell 

 be used to designate the single individuals in a Ilydroid connnunit}', as Ave apply 

 the name Polyps to designate either single Polyps, or single individuals in a Polyp 

 community. The name Strolila is so generally used to designate the stage of 

 Scyphostoma in Avhich the A'ertical axis becomes divided by transA'crse constrictions, 

 and that of Eplu/ra has so long been applied to the 3'oinig Medusa) freed from 

 this axis before they assume their final form, that no further argument is needed 

 to sanction their farther use. Lot it only be remembered, that, as there are Insects 

 with imperfect metamorphosis in Avhich no pupa state is observed, so are there 

 Acalephs in which the lar\a, overleaping the Strobila segmentation, passes directly 

 from the Scyphostoma to the Ephyra state. This is the case in Pelagia (PI. XII. 

 Figs. 4-11). For the adult Acalephs there can be no more appropriate name than 

 that of 3Iediisa\ under Avhich they have ahvays been known. The name of Pi/ndmn 

 for the Medusa) buds ol" the Il^ydroids, and that of Tiidiiincdjvhim for their free 

 Medusa?, are entirely superfluous. 



Were all Acalephs simple animals, this nomenclatm'e Avould 1)0 quite sufficient 

 to describe them aecuratel}'. But in this class, as among Poh'ps, there are a great 

 many species in Avhich the individuals combine to form more or less extensiA-e 

 commiuiities ; and the Acalephs present this additional j^jccidiarit}', that the indi- 



^ This nairn.' should be wi-iUcn Scyphostoma, in aoconUiiK-e with its etymology. 



