736 CHARLES SCHUCHERT 



outside of this area. The last two species, it is true, are Hamilton 

 forms, but it would be claiming too much for them to state that their 

 presence in the Erere formation correlates it with the Hamilton. 

 Knowledge of pelecypods is as yet too fragmentary for safe 

 stratigraphic correlation. The genera present in the Erere are almost 

 without exception those of the Maecuru. The exceptions are: (i) 

 Goniophora, (2) Leda, (3) Pholadella, (4) Edmondia, (5) Tropidocyclus, 

 (6) Pleurotomaria, and (7) Cryphaeus. Numbers i, 6, and 7 are 

 known in the Lower Devonic or in still older formations. Num- 

 bers 2 and 4 have no restricted stratigraphic range. One is there- 

 fore limited to Leda diversa^ Pholadella parallela, and the genus 

 Tropidocyclus. 



Viewing this proposition from another standpoint, it is seen that 

 all the characteristic Hamilton corals, brachiopods, gastropods, and 

 cephalopods are absent in the Erere. This is also true for the 

 Onondaga. 



As the Amazon Devonic deposits are of a littoral nature and the 

 combined known sections about 400 feet in thickness, one should not 

 expect them to represent a long duration of time. At least 100 feet 

 are of Lower Devonic age, comparable with the North American 

 Oriskanian. The remainder appears to be about that of the Onon- 

 daga in age, but from the preceding remarks it seems clear that the two 

 widely separated areas had at this time little, if any, free interchange 

 of faunas. On the other hand, it is clear that there was considerable 

 faunal intercommunication between the seas of Maecuru and the 

 Oriskanian of the southern states of North America. 



The presence of two Genesee brachiopods in the Erere formation — 

 Orbiculoidea lodensis variety and Lingula spatula ? — led Clarke 

 (5:91) to state that "we may regard these beds in the Erere group 

 [black shales] as embodying the equivalent of this Genesee shale 

 fauna." The zone in which the former and three species of Lingula 

 are found is, according to Katzer, the next one below the Erere sand- 

 stone, and it cannot therefore be referred to the horizon of the Genesee 

 without placing there also the entire Erere fauna. The experience 

 of the writer is that Lingula, Orbiculoidea, and other related 

 inarticulate brachiopods have little stratigraphic value for correlation 

 in widely separated areas. 



