190 THE ZOOLOGIST. 



fauna inhabiting these plants. (1) The geographical distribution 

 of many forms of life is affected, since the bromelia-marshes are 

 present over great areas of country where aquatic and amphibious 

 creatures could not otherwise find any habitation. (2) The 

 water being permanent, many bromelia-dwellers have no fixed 

 season for egg-laying, but may be found in various stages of 

 development at all seasons. (3) The purity of the water is of 

 great import, for many animals can live in the bromelia-marsh 

 which could not exist in foul waters. (4) The isolation of the 

 compartments of the " aquarium " affects some creatures. For 

 example, the bromelicolous larvae of certain Megarhine Mos- 

 quitoes are very cannibalistic, and though a number may hatch 

 and start life together in a single compartment, after a time only 

 one survives. Thus frequently a single full-grown larva is found 

 in each compartment, and probably, if the compartments were 

 to intercommunicate, many less larvae would survive than 

 actually do. 



The bromelia-fauna. — Having now considered the nature of 

 its environment, let us turn to the fauna itself. A knowledge of 

 its existence dates back certainly as far as 1879, when Fritz 

 Miiller published his discoveries of certain bromelicolous animals 

 in Brazil. Recently many contributions to the subject have 

 been made by a number of writers. The researches of Calvert 

 and of Picado in Costa Piica have added especially to our know- 

 ledge of this fauna. 



The latter author, in his work already cited, gives a list of 

 about two hundred and fifty bromelicolous species. Many (but 

 not all) of these are considered to be exclusively bromelicolous, 

 i. e. not to occur elsewhere. A full discussion of the reasons for 

 this would be lengthy, but it may be stated that, first, many 

 aquatic animals are found in bromelias over large areas in which 

 there are no other waters suitable for their existence ; secondly, 

 in some cases, when terrestrial waters are present in the vicinity, 

 careful search has failed to reveal in these the presence of the 

 bromelicolous species. 



The opinion is expressed by Picado that, in proportion to the 

 restricted nature of the environment, the bromelia-fauna is as 

 diversified as any in existence. The following groups are 

 actually known to be represented in it : — 



