82 EUCOPIDJE. 



identica. ; as, for example, the Medusae of Eucope polygena, Eucope 

 diapliana, Eucope pyriformis, and Eucope articulata. The strongest 

 case we can cite is perhaps that of Syndictyon and Coryne, the adult 

 Medusa? of which had long been distinguished by the difference of 

 color of the sensitive bulb ; but whether this was anything more than 

 mere individual differences could not be ascertained till Ave became 

 acquainted with the complete development of the former genus, which 

 will be found given in its place in this Catalogue. Hincks, after 

 some observations limited to two genera of Hydroids, came to the 

 conclusion that we could have Medusa?, generically identical, developed 

 from Hydroids generically distinct ; this is so entirely opposed to any- 

 thing known in the history of the development of these animals, and 

 so totally disproved by the examples of Campanularians here described, 

 that I believe that, when the complete history of the two Medusae 

 described by Hincks is fully known, we shall find we have only a case 

 of very close affinity at one stage of their development, and that, as 

 we become acquainted with their more advanced stages, differences will 

 be perceptible. 



The different species of Eucopida? found on our coast, of which we 

 know the development, explain many of the contradictory statements 

 of European writers concerning the mode of development of the dif- 

 ferent species of Eucope. It has been shown only more recently that 

 many of the species, so closely allied as to be readily mistaken at any* 

 time, except the breeding season, were reproduced, on the one hand by 

 Planula?, and on the other by Medusa? ; and now it is found that the 

 Medusa? produced from Hydroids which have been considered identi- 

 cal species, develop into very different adult forms. See, for example, 

 the differences in the Medusa? of Laomedea geniculata, figured by 

 Wright and Gosse ; one has ovaries and the other has none, imme- 

 diately after its escape from the reproductive calycle, as in our Eucope 

 dlapliana and Eucope articulata. The Laomedea yelat'mosa of Van 

 Beneden has twenty-four tentacles and ovaries, as in our Eucope pyrl- 

 formis, to which it is closely allied, while the Medusa of Laomedea 

 (jdat'mosa of English writers has sixteen tentacles at first, and is an 

 Obelia. The European Campanularians require a thorough revision in 

 order to extricate them from the confusion existing in their synonymy, 

 and this can only be done after a thorough acquaintance with the de- 

 velopment of their Medusae. 



The Laomedea dichotoma of Dalyell is probably the same as the 

 Campanularia gelatinosa of Van Beneden. The same confusion oc- 

 curs in the fourth volume of Professor Agassiz's Contributions ; the 

 Eucope which is there figured as Eucope dlapliana Agass., and the 

 Campanularian of that name (Plate 34), is not the Hydroid of Eu- 

 cope diapliana, as will be seen in the description of the latter. The 



