Freshwater Crustacea of the Indian Archipelago. 249 



a species of Oeophagus ; Cirolana elongata, H. M.-Edw., in 

 the mouth of the Ganges ; while Olencira prcegustator, 

 Latrobe, lives upon the coast of North America, but is found 

 besides in rivers in that region. With regard to Glossobius 

 laticauda, M.-Edw., it is stated by Schiodte and Meiuert that 

 it is found in all warm seas upon species of Exocoetus, and 

 when we find the River Continguiba (Maroin) included 

 among the localities, we can only conclude that the authors 

 are here speaking of the mouth of the river, which is probably 

 the only portion sufficiently salt to enable Exoccetus still to 

 exist in it *. 



Now if we further consider that, besides numerous marine 

 species which are inexactly described, we have, especially 

 owing to the work of Schiodte, Meinert, and Hansen, a more 

 precise knowledge of over one hundred and eighty species of 

 Cymothoinae, we shall be obliged to regard this family as 

 genuinely marine, and from the statements and rSsumes given 

 above we may conclude that an immigration into fresh water 

 is partly in progress and partly, as in the case of the three 

 Indian species Ichthyoxenus Jellinghausu, Rocinela typus. 

 and Tachcea lacustris, already completed. 



In our list there also appear two genera nearly allied to the 

 genus Bopyrus, with at least seven species. Semper was the 

 first to announce the occurrence of Bopyrus in the fresh water 

 of the Philippines. Thereupon Giard and Bonnier described 

 Probopyrus ascendens and Palcegyge Borrei, two species which 

 were found living upon freshwater Palaemonids in the Indian 

 Archipelago— the former upon Palcemon lar, Fabr., and the 

 latter upon P. dispar. 



To these I am consequently able to add further forms 

 living upon other species of the genus Palcemon. 



It is well known that the family Bopyrida? is thoroughly 

 marine. Our potamophilous species must therefore be immi- 

 grants into fresh water, and this at the same time implies the 

 assertion that the genus Palcemon has also penetrated from 



* It is true that_J. v. Kennel (< Arbeiten a. d. Zool. Institut zu Wiirz- 

 burg, 1888, p. 276) mentions "a Crustacean belonging to tbe o-erius 

 Jhya ' as having been found by himself in fresh water upon the island of 

 lrimdad ; but no indication whatever of the species is given, as is much 

 to be desired m this case, considering the very ambiguous use that is 

 made of the name JEga. Von Kennel states tbat the occurrence of Mqa 

 in the fresh water of the Palau Islands had already been made known by 

 Semper, and this is also repeated by Simroth. In spite of much search 

 I have not been able to find the statement alluded to. In Semper's 

 ' Existenzbedingungen der Thiers ' (p. 102) a blind « Cymothoon " from 

 " slightly brackish water" is certainly figured, but the genus to which it 

 belongs is not determined. 



