HASEMAN, GEOGRAPHICAL DISTRIB VTION IN SOUTH AMERICA 61 



* Symphysodon, Amazon, 



* Pterophyllum, Amazon, Guiana and Orinoco, 



* Biotoecus, Saraca in Amazon, 



* Paraneetroplus, Rio Sarabia, Mexico. 



According to the static viewpoint of animal geography, we should con- 

 clude from the above data that the Cichlidas originated or dispersed from 

 either the central or the northern part of the Amazon Valley, because 

 sixteen of the twenty-three genera are found there. Five other genera 

 are found only in Central America. All of the seven genera which are 

 found south and east of the Amazon basin are found also in Eio Ama- 

 zonas. Statically, also, we could interpret the entire absence of Cichlidas 

 from Patagonia as meaning that this group had a more northern origin ; 

 but inasmuch as the genus 2E guldens 20 possesses more of the paleotelic 

 characters of the ancestral Cichlidas, it is evident from its distribution 

 that it may have originated in many places not embraced by the mighty 

 Amazon. Also the fact that at least eight of the sixteen Amazonian 

 genera are highly specialized, i. e., cenotelic, may be taken as' evidence 

 that these forms have evolved in this region from less specialized forms 

 whose center of origin was not necessarily in the Amazon. In fact, the 

 Amazon has only two genera which are not found elsewhere in South 

 America, and both of these genera are closely drawn and contain only one 

 species each. Therefore the above list of genera and all that is known 

 about them offer no conclusive evidence that the majority of the living 

 American Cichlidas originated in the Amazon. They may equally well 

 have originated, as far as the above evidence shows, in either Guiana, the 

 Orinoco or anywhere on the old Piano Alto. Before attempting to deter- 

 mine the point of origin of the Cichlidas, I will first put some of the 

 typical genera in their environmental complexes in order to explain their 

 present distribution. 



Eio Uruguay and Rio Gkande do Sul, Including Part of the Lower 



La Plata 



This complex is characterized by medium to low altitudes, sub-tropical 

 to temperate climates, campos, slow flowing water and little or no forests. 

 This region harbors the following species of Cichlidas : 



29 Pellegrin (1904) considers this the most primitive genus, but Crenicara also has 

 many paleotelic characters. 



6— NY 



