24 ANNALS NEW YORK ACADEMY OF SCIENCES 



if the (?) Devonian of Siemiradzki exists there, are good examples of a 

 southern-northern invasion of the sea. In all of this region, an east to 

 west invasion of the sea appears to have been impossible, excepting in 

 narrow belts along the coasts, on account of the intervening Archean 

 mountains, like Serra do Mar, which show no traces of marine deposits. 

 This is of the utmost importance from the standpoint of animal dis- 

 tribution. Some authors have attempted to show that the Patagonian 

 region, and others that the Guiana region, was for a long time cut off 

 from Brazil by arms of the sea. In order to isolate either of the above 

 regions from Brazil, it would require an extensive east to west invasion 

 of the sea for which we have no evidence. On the other hand, the maps 

 showing the location of marine deposits offer strong evidence against 

 such a view- Either the older rocks of Chili or of the Cordova Moun- 

 tains could afford connections between southern South America and the 

 Brazilian region. TTence the observed difference in the fauna of Pata- 

 gonia must be due in a great part to environmental conditions. 10 



BBAZILIAN COAST 



In some respects, the Brazilian coast appears to be the counterpart of 

 the contour of West Africa. Its abruptness is thought by many to be 

 due to the submergence of a "wedge" which originally connected Brazil 

 and Africa. 



Soundings have shown that deep sea exists within a comparatively 

 few miles of the Brazilian coast; but thus far soundings have not pro- 

 duced the slightest evidence for a submerged "wedge" or land-mass 

 which is believed by many to have originally connected Brazil and 

 Africa. In fact, there is strong evidence derived from soundings against 

 the submergence of such an extensive land-mass into the abysmal depths. 



This wedge must have been deeply eroded, forming thereby deep, wide 

 and abrupt valleys. When this surface (such as Brazil at the present 

 time) dropped beneath the ocean, few soundings would be needed to show 

 that the bottom of the ocean under such conditions would not be uni- 

 form. Inasmuch as soundings have revealed no evidence in favor of such 

 a rough sea bottom, 1 take this as strong evidence against such a view. 



It is true that Murray has found a mid- Atlantic ridge, but the trend 

 of this elevation is parallel to the distant coasts, i. e., more or less north 

 and south and not east and west. 



10 Also the imperfection of the fossil records, exploration, etc., in South America can- 

 not he ignored. I saw part of a Toxodon from near Uruguayana, Brazil. Even if an arm 

 of the sea separated Patagonia from the rest of South America, it would have been 

 entirely too narrow to have been an effective barrier. 



