62 memoirs of the carnegie museum 



The Ichthyological Position of British Guiana. 



In the Reports of the Princeton University Expedition to Patagonia, Vol. Ill, 

 I discuss, among other things, the distribution of the fishes in the Americas south 

 of the tropic of Cancer. Five distinct regions of unequal value are recognized: 

 (1) Transition, (2) Mexican, (3) Brazilian, (4) Andean, and (5) Patagonian. 



In the Brazilian region the following "provinces" were enumerated: (1) Central 

 America, (2) Pacific, (3) Magdalena, (4) Amazon, (5) Guiana, (6) Trinidad, (7) 16 

 San Francisco, (8) Coastal, (9) La Plata, the latter divided into the Paraguay and 

 Parana-La Plata. 



Concerning the Guiana Province, including French, Dutch, British, and Vene- 

 zuelan Guiana, the following is said (p. 319) : 



"The Guiana Province, including one of the oldest land-masses, is drained 

 by the Cachipur, Oyapoc, Cayenne, Mana, Maroni, Surinam, Corentine, Essequibo 

 (Mazaruni, Cuyuni, Rupununi and other tributaries of the Essequibo), Demerara, 

 Berbice, by the Orinoco and its eastern and southern tributaries, the Caroni, Caura, 

 Ventuari, and by the Rio Branco, and the northern tributaries of the Amazon east 

 of the Branco. 



"The feature distinguishing this region is the known or reported connection 

 between neighboring streams. The Cassiquiari connects the Orinoco with the Rio 

 Negro. The Atabapo is said during the rainy season to be connected with the 

 Guaina, and the Rupununi of the Essequibo basin with the Tacutu of the Rio 

 Branco basin. It is said that the Essequibo is also connected with the Rio Trom- 

 betas through the Apini and the Oyapoc, Cachipur, and Araguary with the tribu- 

 taries of the Yari, which empties into the Amazon. 



"The lower course of the Essequibo of British Guiana at least is connected 

 with the lower Orinoco by natural canals, so that these form part of the Orinoco- 

 Amazon-La Plata meshwork and contain the same types. The Eastern Guianas 

 (French) have a less varied fauna. 



"The fauna of this region is of the greatest importance to theoretical chorology, 

 since this is one of the two old land-masses, and since it was by a continuation of 

 this area that South America is supposed to have been connected with Africa. 



"Our knowledge of the fish fauna of this region is derived from Muller & 

 Troschel's account of the fishes of British Guiana; Bleeker's Silure de Surinam; 

 Vaillant's notes on the fishes of French Guiana, and his account of the Berbice and 

 the general work of Cuvier & Valenciennes, Gunther, Eigenmann & Eigenmann, 

 Regan and Pellegrin. 



16 "East Brazilian Plateau," comprising 7 and S, was given a separate heading in the paper quoted. 



