186 MUGGIAEA. 



huxleyi (Haeckel), and M. atlantica Cunningham. The Diphyes chamissonis 

 of Huxley, referred to this genus by Haeckel, proves to be a true Diphyid (p. 244). 

 Diphyes arctica Chun, is likewise classed here by Schneider ('98, p. 89) on the 

 ground that the "einmal beobachtete Schwimmglocken-anlage diirfte eher einem 

 Rudiment als einer Ersatzglocke entsprechen." But so far as we know, neither 

 rudimentary nor reserve bells occur among the Monophyidae; and it is there- 

 fore better to retain arctica among the Diphyidae, at least until it is known 

 whether or not a posterior nectophore is normally pret-ent. 



Neither Chun ('92) nor Schneider ('98) recognize M. pyramidalis Haeckel 

 as distinct from M. kochii. According to Haeckel pyramidalis "differs from 

 the former [kochii] mainly in the size of the conical hydroecium, the top of 

 which attains half the length of the nectosac" ('88b, p. 137). This particular 

 feature i. e. length of the hydroecium, is so important among Diphyids, that it 

 might be expected to be significant in the case of Muggiaea. And Cunningham's 

 ('92, p. 214) studies of large series of this genus from Plymouth, England, have 

 proved that such is the case. HisM. atlantica is easily separated from M. kochii 

 by the great length of the hydroecium, and by the fact that the somatocyst, 

 reaching barely to the mid-level of the nectosac in kochii, reaches to its apex, or 

 even beyond it in atlantica. I have myself been able to test these characters 

 in series of the former both from the Atlantic ( :11b, p. .340) and the Pacific, and 

 of the latter from the Pacific, with the result that they prove so constant as to 

 be valuable for diagnosis. Cunningham thought it extremely probable that 

 the form observed by Haeckel at the Canary Islands was the same species as 

 that which he obtained at Plymouth, and no doubt this view is correct. 

 Haeckel's name, however, cannot be used, because preoccupied by Busch for 

 M. kochii; and atlantica must therefore be applied to the compound species 

 characterized by deep hydroecium and long somatocyst. The status of M. 

 huxleyi, known from one record only, is doubtful. Chun ('86) has worked out 

 the development of M. kochii, finding that the primitive bell is soon lost, 

 and that the definitive nectophore is a secondary structure. M. kochii is known 

 from the Mediterranean, the Canaries (Chun '86), and the Bay of Biscay (Bige- 

 low :11b), M. atlantica from the Canaries (Haeckel) from the English Channel 

 and the Irish Sea (p. 376). It has also been recorded from Skagerak, but this 

 record probably belongs to Diphtjes arctica (p. 188) ; and the capture of both in 

 the Eastern Tropical Pacific, shows that their distribution is parallel in the 

 warmer parts of both oceans. 



