BIGELOW : MEDUSAE FKOM THE MALDIVE ISLANDS. 



247 



shown in the following tabic. The mark signifies tliat tlie species 

 is represented by an exceedingly closely allied, if not identical form. 



Considered from the standpoint of morphology, many of the new 

 species are of interest, since they differ from their nearest allies in 

 important structural characters. Such species are : Euphysa tetrabrachia, 

 the only Euphysa possessing three prominent short tentacles ; Timoides 

 agassizii, the only Leptomedusa possessing blind centripetal canals in 

 the hell wall ; Aurelia maldivensis, the only Aurelia with long pendent 

 mouth parts. Taken as a whole, the new species uniformly show a 

 very decided separation from their near allies in the Atlantic and 

 Pacific, and there is only one, Dipurena fragilis, which seems to be 

 a geographic race of a well-known Atlantic form. 



The Maldive islands form in every respect a typical tropical coral reef 

 reo-ion. and a comparison of their Medusa fauna with that of similar 

 re<);ions in the Pacific and Atlantic is therefore of interest. Such other 

 regions, of wdiich the Medusae have been studied, by A. Agassiz and 

 A. G. Mayer (see Mayer, Bull. Mus. Comp. Zool., vol. 37, and Agassiz 

 and Mayei', Bull. Mus. Comp. Zool., vol. 32, no. 9), are the Fiji Islands 

 and the Tortugas. 



Taking first Fiji, we find the following conditions. The two areas 

 have in common the following thirteen genera : Aeginella, Aglaura, 

 Bougainvillia, Eirene, Eutimeta, Gonionemus, Liriope, Oceania, Aure- 

 lia, Nausithoe, Beroe, Diphyopsis, and Physalia. But of these thirteen 

 only four are represented by the same species. These are Aeginella 



