6 On some Fish- remains from the Parana Formation. 



11. Undetermined Siluroids dsc. 



Remains of Siluroid fisliea are very abundant in the Parana 

 formation, but all the known specimens are too fragmentary 

 for exact determination. They evidently represent Ariiis, 

 Ptinehdtis, Platystoma, and other genera which still live iu 

 the fresh waters of South America. 



Fragments of Characinoids also occur and are easily recog- 

 nized ; but other remains, such as those which have been 

 referred to Sparoids and Labroids by Bravard and Alessandri, 

 are not satisfactorily determinable. The so-called tooth of 

 l^ejyidostens described by Alessandri {loc. cit. p. 726, pi. i. 

 fig. 8) is not sufficient to indicate the presence of this genus. 



If the foregoing determinations of the fish-remains from the 

 Parana formation be accepted, it is evident that Alessandri's 

 argument for the Eocene age of this deposit has no founda- 

 tion in fact. The so-called teeth of Acrodus and Corax 

 (which are typically Mesozoic genera) become, on renewed 

 examination, evidence of Cestracion and Carcharias, which 

 range throughout the Tertiary formations and survive at the 

 present day. It is by no means certain that the teeth deter- 

 mined as Odontaspis elegans in the Parana collection belong 

 to the same fish as those originally thus named in European 

 Eocene collections ; and even if Carchnrias (Aprionodon) 

 Gibbesi were correctly identified, the Piiospliates of South 

 Carolina, from which tiie type specimetis of that species were 

 obtained, seem to include fossils of all Tertiary ages from the 

 Eocene to the Pleistocene. In fact, the only species in the 

 Parana collection which seem to be of real importance for 

 stratigraphical purposes are Oxyrhina hastalis, Carcharodon 

 megalodon, and Ilemi'pristis serra. All these in Europe 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, not of typical size like those from Parana. Moreover, 

 it 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 *, this 

 discovery probably implying that these great sharks did not 

 become extinct until quite the latest geological times. I 

 therefore conclude, witii Burmeister and Stelzner, that the 



* J. Mm ray and A. Kenard, "Deep-sea Deposits" ('Challenger' 

 Keports, 1801), pis. v., vi. 



