GEOLOGICAL PAPERS IO7 



Feet. In. 



Spirifer asper^ Hall * * * * 



Spirifer biiitesialis. Hall * * 



Spirifer euryteines, Owen * * * 



Spirifer iozcensis, Owen * * * 



Spirifer subvaricosus, Hall and Whitfield * * * 



Stropheodonta concaz-a. Hall * * * * 



Stropheodonta demissa, Conrad * * * * * 



Stropheodonta perplaua. Conrad * * * 



Bellerophon pelops, Hall * * 



Phanerotinus exiguus. Kindle * * * 



Platyceras dumosum, Conrad * * * 



Pleurotomaria luciita. Hall * 



Tentaculites bellulus, Hall * * * * 



Actinopteria decussata, Hall * * 



Aviculopecten sp 



Conocardium cuneus altum. Keyes * * 



Cypricardelia bellistriaia. Conrad * * * 



Cypricardiuia itideufa. Conrad * * * * * 



Edmondia sp 



Goniophora sp * 



Modiola sp 



Modiomorpha concentrica. Hall * * 



Mytilarca trigonale, Cleland * * 



Mytilops prcccedens. Hall * * 



Paleoneilo cf. plana, Hall * * * * * 



Paracyclas elliptica. Hall * * * * 



Paracyclas lirata, Conrad * * * * 



Pterinopecten sp * 



Ptychopteria eucrate, Hall * 



Ptychopteria sao, Hall * 



Sphenotus sp 



Gomphoceras ajax, Hall . . . .- * * 



Gyroceras pratti. Barris * * 



Dahnanites barrisi. Hall * 



Phacops raiia, Green * * * * * 



P rectus cf. occidens, Hall 



COXCLUSIOX. 



A Study of the foregoing list of fossils found in the Devonian 

 strata in Rock Island county leaves no doubt that they are more 

 closely related to the fauna of the Dakotanor Northwest province 

 of the Hamilton division of the Devonian than to the Xew York 

 or. Eastern province. Of the total number of ninety-seven species 

 determined, eighty-one, or 83 per cent, are found elsewhere in the 

 Dakotan province, and of these eighty-one species, forty-two, or 

 51 per cent, are found exclusively in this province. Of the fifty- 

 five species occurring also in the Eastern province, all are wide- 

 spread forms, and have a general distribution, none being dis- 

 tinctively Eastern species. Of the "Standard list of dominant 

 species for the Xew York-Ontario province" (Eastern ^Middle 

 Devonian), which Williams^ has established, only two. Phacops 



* Williams. H. S.. Am. Tour. Sci.. Vol. XIN', 4th ser.. 1912. 



