125 



S. 56 w. Hard, gray to drab limestone 1 foot, 8 inches. 



Atrypa reticularis r, Schuchertella clieiniiiigensis arctistriata c, 



Chonetes yandellanus r, Spirifer sp. r, 



Nucleospira concinna r, Spirifer varicosus r, 



Pholidostrophia iowensis c, Strophalosia truncata a, 



Pnoductella spinuUcosta a, Paracyclas elliptica c, 



Schisophoria propinqna r, Gyroceras sp. r. 



S 56 X. Hard, dark gray limestone, with many small nodules of 

 chert in the upper three feet, and a zone of Chonetes eight inches be- 

 low the chert 5 feet, 6 inches. 



Chonetes konickianus c, Spirifer gregarius var. r, 



Pholidostrophia iowensis c, Phacops rana r, 



Productella spinuUcosta r, Tentaculites scalariformis r 



S 56 y. Massive ledge of hard, gray, sub-crystalline lime- 

 stone 7 feet, 6 inches. 



Cyathophyllum rugosum c, Spirifer grvgarius r, 



Favosites emmonsi c, Spirifer gregarius var. a, 



Cystodictya meeki r, Spirifer scgmentus c, 



Chonetes konickianus c, Strophalosia truncata r, 



Chonetes yandellanus c, Stropheodonta concava c, 



Cyrtina hamiltonensis c, Leptodesma sp. r, 



Eunella sullivanti r, Loxonema sp. r, 



Pholidostrophia iowensis a, Bellerophon pelops r, 



Productella spinuUcosta a, Platyceras blatchleyi r 

 Cf. Camarophoria gainesi (young) r. 



Immediately above S 56 y the lithology changes abruptly from 

 massive, subcrystalline limestone below, to thinner bedded, more 

 argillaceous material above. Above this member the character- 

 istic Onondaga fossils Cyathophyllum rugosum, Chonetes konick- 

 ianus, C. yandellanus, Eunella sullivanti, Spirifer gregarius, and its 

 variety, S. segmentus, Bellerophon pelops and Platyceras blatch- 

 leyi have disappeared. In their places such Hamilton species as 

 Microcyclus discus, Chonetes pusillus, Eunella attenuata, Spirifer 

 fornacula, S. divaricatus and Actinopteria boydi become the con- 

 spicuous froms. 



There is given in tabular form below a list of the fossils col- 

 lected from the Grand Tower formation in Illinois. In this 

 table the species having a star prefixed to their names, occur 

 in the sandstone member at the base. In column No. 1, on 

 the right, there are indicated by a cross those species occurring 

 in the Grand Towner strata, below the horizon of S. 56 h of 

 the major section, which have also been reported by Kindle^ 

 from the Jeffersonville beds of Indiana. In column No. 2 there 

 are shown by a cross those Jefifersonville species which are 



iKindle: Devonian Fossils and Stratigraphy of Indiana. 25th Ann. Rept. Gecl. 

 and Nat. Hist, of Ind., 1900. 



