118 SOLLAS On the Origin of Freshwater Faunas. 



NOTE I. Since this Paper was in type, Professor Ray Lankester has kindly 

 called my attention to some observations by Dr. J. Von Kennel,* who describes 

 certain lagoons bordering the coast of Trinidad, which communicate at times with 

 the sea, and so receive a number of marine inhabitants ; and when subsequently 

 the water of the lagoon becomes fresh, several of the marine forms, adapting 

 themselves to the changed conditions, continue to live on, and amongst others 

 thus persisting is a Medusa, which Dr. Kennel regards as different from Limnoco- 

 dium, without, however, specifically determining it. 



Besides this repetition by Nature of Beudant's experiments, Dr. Kennel gives 

 a very clear instance of the direct introduction of marine forms into a river due 

 probably to the transportation of free-swimming larvae by tidal agency thus, he 

 mentions Mytilacea3, a small species of Pholas, and Lumbriconereis, as existing in 

 the freshwater of the river Ortoire, eight miles above its mouth. 



NOTE II. The occurrence as freshwater forms of marine animals which 

 inhabit floating timber is very suggestive from two points of view, for first it 

 leads one to infer that, in such cases, means of transport being afforded, adapta- 

 tion to freshwater conditions follows readily ; and next, since such instances are 

 rare, that to inhabit freshwater is only the first step towards becoming a 

 characteristic freshwater organism; till the developmental history also becomes 

 modified a wide distribution is not probable. Hence I would call special attention 

 to Prof. E. Perceval Wright's remarks on this subject in a Paper describing a 

 freshwater Teredo (Nausitora Dunlopei) in the waters of the river Hurreegonga a 

 tributary of the Ganges.f 



* Biologische u. faunistische Notizen aus Trinidad, Arb. d. Zool.-zoot. Instituts in Wurzburg ; Ed. 

 vi., 1883. 



t On a new genus of Teredininas, by E. Perceval Wright, M.D., Transactions Linnaan Society, Vol. 

 xxvii., p. 451 (1864). 



