GEOLOGY OF THE LOWER AMAZON REGION 735 



nettoana (Clarke thinks that the small Erere specimens should be 

 separated from the larger Maecuru form), Vitulina pustulosa, Schu- 

 chertella agassizi, Chonetes comstocki, C. herbert-smithij Camaro- 

 toechia dotis ? ?, Spirifer pedroanus, Trigeria ( ?) wardiana, T. ( ?) 

 jamesiana^ and Tentaculites eldredgianus. None of these perduring 

 species appear to have significant stratigraphic value, either for 

 Middle or Lower Devonic correlation. 



Concerning the species restricted to the sandstone horizon, the 

 following notes will help to a clearer understanding : Lingula spatulata 

 is certainly not this New York Upper Devonic species. Orhiculoidea 

 lodensis may be the New York Genesee form. However, any student 

 of brachiopods knows how variable the species of those genera are, 

 and that no safe identification can be made in similar forms so widely 

 separated as those of the state of Para, Brazil, and Kentucky. This 

 is because in Lingula and Orhiculoidea there are so few characters 

 present for comparison; further, when the shells are preserved in 

 shales, they are invariably flattened. On the other hand, Orhiculoi- 

 dea lodensis occurs beneath the Erere fauna and not above it. 

 Tropidoleptus carinatus in North America is now known in the Oris- 

 kanian, Hamilton, and Chemung, and is no longer diagnostic for the 

 Middle Devonic of this continent. Vitulina pustulosa^ it is true, is 

 known only in the Hamilton of North America, but in South America 

 it certainly occurs in older formations. Chonetes onettianus is related 

 to C. scitula of the Hamilton and Chemung. Clarke suggests that 

 Spirifer pedroanus may include two species similar to 5. mucronatus 

 and S. audaculus, two characteristic Middle Devonic forms. This 

 species, however, as figured by Katzer, recalls the Lower Devonic 

 S. cumberlandiae. Modiomorpha pimentana seems to be related to 

 M. concentrica of the Hamilton. Nuculites ererensis suggests N. 

 oblongata of the Hamilton. Leda diversa Hall and Pholadella paral- 

 lela Hall are Hamilton species. The other forms not noted here do 

 not teach anything specifically from the standpoint of the Hamilton 

 or of the Middle Devonic. 



In the Erere fauna there are therefore four Hamilton species — 

 Tropidoleptus carinatus ^ Vitulina pustulosa^ Leda diversa^ and Phola- 

 della parallela. The first is no longer regarded as diagnostic for 

 limited correlation within the Mississippian sea, and the second, 



