GEOLOGICAL PAPERS IO3 



Feet. In. 

 Ltd. Layer of yellowish, rather shaly Hmestone which weathers 



readily. Fossils resembling those of EiC 9 



Cyathophyllum sp. Productella subalata 



Cystiphyllum cf. americanum Schizophoria striatula 

 Streptelasma simplex Spirifer iozceusis 



Atrypa hystrix Stropheodonta demissa 



Atrypa reticularis Stropheodonta perplana 



Atrypa spinosa Platyceras dumosum 



CraucBua iozcetisis Pleurotomaria lucina 



Gomphoceras ajax 



EiC Outcrop under and just south of the Rock Island Ry. bridge, 

 in the S.E. J4 sec. 24, T. 17 X.. R. i W. Very hard, fine- 

 grained limestone containing manj- corals. May be desig- 

 nated as the Phillipsastrea horizon i 3 



Astraeospongia hamiltonensis Zaphrentis sp. 



Alveolites goldfussi Hemitrypa tenera 



Acervularia davidsoni Orbignyella montictila 



Acerz'ularia profunda Atrypa hystrix 



Ceratopora sp. Atrypa reticularis 



Cladopora palmata Crancena romingeri 



Cladopora sp. Gypidula coinis 



Craspedophyllum archiaci Xucleospira ventricosa 



Cyathophyllum sp. Productella subalata 



Cystiphyllum americanum Reticularia subundifera 



Favosites alpenensis Schizophoria striatula 



Favosites hamiltonensis Spirifer euryteines 



Favosites placenta Spirifer iozcensis 



Heliophyllum halli ^Stropheodonta demissa 



Phillipsastrea billingsi Bellerophon pelops 



Streptelasma simplex Pleurotomaria lucina 



Gomphoceras sp. 



Eib. Stratum of hard, gray limestone, just above the breccia, and 



below Phillipsastrea zone, containing the fossils i 3 



Zaphrentis sp. Pholidostrophia iowensis 



Athyris fultonensis Productella subalata 



Atrypa hystrix Reticularia fimbriata 



Atrypa reticularis Spirifer subvaricosus 



CrancBna iozvensis Stropheodonta demissa 



Cyrtina hamiltonensis Bellerophon pelops 



Pentamerella dubia • Pleurotomaria lucina 



Gomphoceras 



Eia. Outcrop in bed of ^lill Creek, one-half mile east of Milan, 

 north and south of wagon bridge. Dark-gray, fine-grained, 

 much brecciated limestone, bearing no fossils lO 



The members of the section from the bottom up to the Acen-u- 

 laria davidsoni coral reef are clearly separable into two general 

 divisions : the lower, softer and more yellow is thinly stratified ; 

 the upper, harder and more brown, is in thicker layers. In both 

 portions the jointing is not nearly so close together and is more 

 nearly perpendicular to the bedding planes than in the members 

 Ejg to Ejj, inclusive. The latter members are distinctly and 

 characteristically obliquely jointed, and shattered and broken into 

 small, very sharp and angular blocks. 



The uppermost member of the Mill Creek section, Ejp, may be 



