712 SCHUCHERT AND TWENHOFEL ORDOVICIC-SILURIC SECTION 



circula, Orthis jidbellites, Rafinesquina profunda, Rhynchonella hidens, 

 Strichlandinia lens, Atrypa reticularis (first appearence), Hyattella 

 congesta, Platyceras, and Oalymene cf. vogdesi. However, when one 

 attempts to correlate this zone with any of the Clinton formations of the 

 United States difficulties at once beset the comparisons, because the lower 

 Gnn Eiver fanna is a generalized assemblage, having species that are 

 restricted either to the Appalachian area, western New York, or the Ohio 

 region. 



The same generalized Clinton assemblage also marks the upper G-nn 

 Eiver in the Triplecia ortoni beds. Here the New York, or Appalachian, 

 species, Rhynchonella hidens, Strichlandinia lens, Pentamerus ohlongus 

 (first appearance in this zone, and then remains thronghont the higher 

 beds to the end of E), Anoplotheca hemispherica (same range as last 

 species), and Hyattella co7igesta^ are associated with Triplecia ortoni. 

 The latter, elsewhere than Anticosti, is only seen in the region of the 

 Cincinnati axis from Ohio to Oklahoma, and in Alabama, where it occurs 

 underneath the Eockwood Clinton. 



The Ohio Clinton is devoid of Pentamerus ohlongus, Atrypa reticularis, 

 and Anoplotheca hemispherica, brachiopods unknown in the lower Gnn 

 Eiver formation. If these are reliable time indicators, then it may be 

 said that the Ohio Clinton holds abont the time of the lower Gun Eiver 

 and that in the south Triplecia oi^toni appears in profusion earlier than 

 on Anticosti, as here this form is not common until in upper Gun Eiver 

 time. If, on the other hand, it is held that the guide fossils appear some- 

 what earlier on Anticosti, then the Ohio Clinton would seem to hold the 

 time of Dg of the Gun Eiver formation up to the top of Eg of the Jupiter 

 Eiver formation. Triplecia ortoni ranges here through 279 feet of strata, 

 whereas along the Cincinnati axis this form is apparently restricted to 

 less than 25 feet of limestones. 



The lower fossilifcrous Clinton of the Eochester, New York, region 



(Wolcott limestone) appears not to be older than the upper Gun Eiver, 



for the diagnostic fossils Bilohites hilohus, Pentamerus ohlongus, Atrypa 



reticularis, Rhynchonella hidens^ Hyattella congesta^ and Anoplotheca 



. hemispherica are common to both formations. 



It appears probable that some of the diagnostic Clinton fossils appear 

 earlier on Anticosti than in the United States. This seems to be true for 

 Hyattella congesta, Strichlandinia lens, Pentamerus ohlongus, Rhipido- 

 mella circula, Anoplotheca hemispherica, Atrypa marginalis, A. reticu- 

 laris, and some of the corals. It is this that leads the writers to correlate 

 the Clinton formations of the United States with apparently somewhat 

 later similar faunal occurrences on Anticosti. 



