Chap. VI. GEOGRAPHICAL DISTRIBUTION. 



179 



loma, have been found. Among the low islands of the Pacific, Leptobrachia 

 leptopus, Crossostoma frondosa, if identical with that of China, Diplopihis Couthouyi, 

 Polyclonia Mertensii, a species of Aurelia, Pelagia panopyra, if identical with that of 

 Australia, and P. Labiche, Cunina globosa, Eurybia exigua, Scyphis mucilaginosa, and 

 Polyxenia flavibrachia. Between the Sunda Islands and New Guinea, Cassiopea 

 Andromeda, if identical with that of the Red Sea, Hydroticus rufus, Mastigias papua, 

 Thysanostoma Lessoni, Salamis toreumata, Homopneusis frondosus, Campanella capi- 

 tulum, ^gina semirosea, Marsupialis flagellata, and Bursarius Cytherese. The prev- 

 alence of Rliizostomea3, in this part of the ocean, to the complete exclusion of other 

 large DiscophoriB, is very striking. In the Indian Ocean, Catostylus Wilkesii, 

 Toxoclytus Dubreuillii, and Stenoptycha caliparea. In the Red Sea, Rhizostoma 

 corona and tetrastylum, Leptobrachia lorifera, Cassiopea Andromeda, Cephea octostyla, 

 Polyrhiza Cephea and vesiculosa, and a species of Aurelia. Almost none but Rhi- 

 zostomejB; a striking contrast with the western coast of North and South America, 

 where no Rhizostoraefe have yet been found. 



Around Australia, to the north of it, Melita purpurea; to the west, Evagora 

 capillata, Polyrhiza fusca, Polyclonia theophila, Favonia octonema, Aurelia lineolata, 

 Pelagia panopyra, and ^gina cyanogramma and grisea; to the east, Catostylus 

 mosaicus and Stenoptycha rosea; to the south, Limnorea triedra, Chrysaora pen- 

 tastoma and hexastoma, Euryale antarctica, and Pegasia cylindrella. Off New 

 Zealand, Aurelia clausa. 



In the North Pacific, about the 36° of N. Lat, Pelagia flaveola, ^gina citrina 

 and rosea, and Scyphis punctata have been found; in California, a species of Poly- 

 bostrycha, and one of Melanaster; and in China, Hymantostoma Sueurii, Crosso- 

 stoma frondosa, Phyllorrhiza chinensis, and Donacostoma Woodii. 



It thus appears that nothing whatsoever is known of the Acalephs of Japan, 

 and very little of those of the west coast of Africa, and South America, judging' 

 from the few species enumerated above. Those of the east coast of Africa, with 

 the exception of the Red Sea, are also entirely unknown. It can hardly be doubted 

 that the Pacific and Indian Oceans, and the seas south of Tasmania and Terra 

 del Fuego, will yet yield a richer harvest of Acalephs than has thus flir been 

 gathered there. From want of materials, the precise limits of the Acalephian 

 Faunaj, alluded to above, cannot yet be determined. From the facts observed along 

 the coasts of North America and of Europe, I have no doubt, however, that the 

 principle of limitation of the Fauna^ which I have pointed out, in my third Report 

 of the Museum of Comparative Zoology at Harvard, will also be applicable to the 

 Acalephs. Natural Faunje, as far as I have been able to trace them, are defined 

 by the geographical range of representative species living in adjoining regions. 

 This principle has already been tested, for the Discophora;, by the geographical 



