EUCOPID^E. 81 



ORTHOPYXIS AGASS. 



OrtJiopyxis AGASS. Cont. Nat. Hist. U. S., IV. pp. 297, 355. 1862. 

 Clytia LAMX (p.p.). Bull. Soc. Phil. 1812. 

 ? Silicularia MEYEX. Nov. Act., XVI. 1834. 



Orthopyxis poterium AGASS. 



OrtJiopyxis poterium AGASS. Cont. Nat. Hist. U. S., IV. pp. 297, 302, Fig. 40; p. 355; Pis. 28, 29, 

 Figs. 1-5. 1862. 



Massachusetts Bay (Agassiz) ; Nova Scotia (Anticosti Expedition). 

 Cat. No. 125, Nahant, April, 1856, H. J. Clark. Hydromedusarium. 

 Cat. No. 126, Naliant, June, 1861, A. Agassiz. Hydrarinm. 

 Cat. No. 127, Naliant, July, 1861, A. Agassiz. Hydrarium. 

 Cat. No. 128, Naliant, August, 1861, A. Agassiz. Hydrarium. 

 Cat. No. 129, Naliant, September, 1854, H. J. Clark. Hydrarium. 

 Cat. No. 130, Naliant, December, 1854, H. J. Clark. Hydrarium. 

 Cat. No. 131, Naliant, March, 1856, H. J. Clark. Hydrarium. 

 Cat. No. 400, Naliant, Mass., 1862, A. Agassiz. 

 Cat. No. 414, Mingan Islands, N. S., Anticosti Expedition, 1861. 

 Museum Diagram No. 18, after L. Agassiz. 



Family EUCOPID^E Gegenb. 



Eucopiclce GEG. (emend Agass.). Zeit. f. Wiss. Zool., p. 241. 1856. 

 Eucopidce AGASS. Cont. Nat. Hist. U. S., IV. p. 351. 1862. 



Great confusion has always existed in the identifications made of the 

 different species of Campanularians, on account of the difficulty of dis- 

 tinguishing in certain stages closely allied species. If, however, we 

 are fortunate enough to examine them at the breeding season, when 

 the characteristic reproductive calycles of the different species are in 

 their full development, our task will be greatly facilitated ; and any 

 doubts we may still have of the identity or difference of closely allied 

 species will be entirely removed, should we succeed in tracing the 

 development of the young Medusa. Although we may find it impos- 

 sible to distinguish, at certain stages of growth, young Medusce, it 

 by no means follows that these Medusae, which have developed from 

 Campanularians easily distinguished, are identical. (Compare the dif- 

 ferent Campanularians figured in the sequel.) Whenever we succeed 

 in tracing the complete history of any one of our Jelly-fishes, we 

 always find that we are able to distinguish readily closely allied 

 species, which our previous ignorance had led us to consider as 



XO. II. 11 



