HASEJIAX, GEOGRAPHICAL DISTRIBUTION IN SOUTH AMERICA 59 



HopJias malabricus, Bloch. 

 Acestorhynchus falcatus, Bloch. 

 Hoplerythrinus unitceniatus, Spix. 

 Characidium fasciatum, Reinhardt. 

 Carimatus elegans, Steindachner. 

 Creatoclianes sp. ? 



MoenJchausia oligolepsis (?) Gunther. 

 Astaynax bimaculatus, Linnaeus. 

 Crenicichla lepidota, Heckel. 

 Cichlasoma bimaculatum, Linnaeus. 



A similar paucity of species has been noted by Eigenmann in the high- 

 lands of Guiana. He has kindly given me the following list which he 

 collected above the Kaieteur Falls : 



Rhamdia quelens 

 Heleogen es m arm of a t us 

 ' Pydidium guianense 

 Callichthys callichthys 

 Lithogenes villosiis 

 Corymbophancs andersoni 

 Phyrruhlina filamcntosa 

 Pcecilochdrax bovalli 

 Moenkh ausia oligolepis 

 Moenkliausia brownii 

 Creatoclianes affinis 



Poecilurichthys bim aculatus 

 Astyanax mutator 

 Hoplias malabricus 

 Hoplerythrinus unitam iatus 

 Erythrin us erythrinus 

 Gymnotus carapo 

 Hypopom us brevirostris 

 Rivulus holmiw 

 /Equidens potarensis 

 Heterogramma ortmanni 

 Crenicichla alta 



It is at once evident from the above that there have never been found 

 more than twenty-five species in any one locality on the Piano Alto. 

 Compiling the possible lists from various localities, however, we might 

 obtain as many as fifty species as inhabitants of the Piano Alto. If we 

 even doubled this probable list, there would still be about fifty species, 

 many belonging to lowland genera common to the Paraguay and Amazon 

 valleys, to account for in some other way than by a possible overland 

 passage. Hence other factors than mere land-bridges, river connections, 

 etc., are involved in the present distribution of South American fishes. 



It has already been stated that the highland genera, usually small in 

 size and widely distributed, are the generalized types which have pro- 

 duced the bulk of the ichthyological fauna. In fact, the highland genera 

 which I have enumerated include 33 per cent of the 1917 species which 

 have been reported from South and Central America by Eigenmann. 

 The highland genera of Cichlidge include 150 of the 187 species of Cich- 

 lidge reported by Eigenmann from South and Central America. 



The above statistics are sufficient to show that most of the purely fresh- 

 water fishes are directly related to the highland genera which continue to 



