L'AGE DES FORMATIONS SÉD1MENTAIRES DE PATAGONIE 249 



wich seem to be of real importance for statigraphical purposes 

 are Oxyrhina hastalis, Carcharodon megalodon and Hemipristis 

 serra : Al 1 these i n Europa are exclusively Miocene and Pliocene 

 fossils, while the only teeth from the undoubted Eocene of North 

 America (Alabama) commonly referred to the same species are 

 comparatively small, no of typical size like those from Paraná. 

 Moreover, i l is to be noted that several teeth of Oxyrhina hastalis 

 and Carcharodon megalodon were dredged from the bed of the 

 South Pacific Ocean by the «Challenger expedition », ti i i s discovery 

 probably implying that these great sharks dit not become extinct 

 until quite latest geological times. I therefore conclude, with 

 Burmeister and Stelzner, that the Paraná formation is truly oflate 

 Tertiary age, an may probably be correlated with the pliocene of 

 the norlhern hemisphere» (10*9, p. 6-7). 



(A suivre). 



