CORRELATION 325 



crinoidal elements in the Saint Joe fauna are essentially unknown, but 

 forms similar to those in the Fern Glen may be looked for. 



The exact correlation of the Fern Glen with some part of the Saint 

 Joe formation as it was interpreted by the members of the late Geo- 

 logical Survey of Arkansas may be assumed to be established. Unpub- 

 lished data gathered by Dr E. 0. Ulrich, however, suggest that a lower 

 member, perhaps separated by a slight unconformity from the typical 

 Saint Joe marble, was not sufficiently differentiated by the members of 

 the Arkansas Survey. These lower beds are commonly fossiliferous, 

 while good fossils are comparatively rare in the Saint Joe proper, and it 

 is from these lower beds that most, if not all, of the material recorded by 

 Williams was probably obtained. The exact correlation of the Fern 

 Glen beds, therefore, will probably prove to be with these beds which are 

 immediately subjacent to the typical Saint Joe marble, but which have 

 been commonly united with that formation as a single formation unit. 



THE NEW PROVIDENCE SHALE 



The name New Providence shale was first applied many years ago to 

 the basal portion of the so-called Knobstone group in southern Indiana 

 by Borden, 11 and has been revived more recently by Newsom. 12 The 

 formation includes from 50 to 120 feet of shales which immediatelv 

 overlie the Eockford goniatite limestone, which carries a fauna with 

 strong Chouteau affinities. The fauna of the New Providence shales in 

 Indiana has been made known in an inadequate manner, the list fur- 

 nished by Newsom 13 being incomplete and having some of the identifica- 

 tions probably incorrect. 



The same formation extends into Kentucky, and a locality at Button 

 Mould knob, south of Louisville, has been mentioned not infrequently 

 by the older collectors of fossils from that region. A small collection of 

 material from this locality has been available for study by the writer, 

 which shows the fauna to be rich in small corals, among which are sev- 

 eral species of Cyathaxonia, including C. cynodon E. & H., which was 

 apparently originally described from this or a neighboring locality. This 

 genus is one of the most common in the Fern Glen fauna, and although 

 the species in the two localities seem to be different, they are somewhat 

 closely allied. Among the other corals, the species described in the pres- 

 ent paper as Amplexvs rugosus is represented in the Button Mould Knob 

 fauna by perfectly typical examples, and Monilopora crassa is also com- 



11 Fifth Annual Report of the Geological Survey of Indiana, p. 161. 



12 Twenty-sixth Annual Report of the Geological Survey of Indiana, p. 261. 



13 Loc. cit, p. 278. 



