Report of the State Geologist. 



357 



Schoharie Grit. 



The rich Crustacean fauna of these rocks is exclusively trilobitic, 

 and consists of eighteen species from the localized development 

 of the formation in eastern New York. These are : 



Calymene platys. 

 Phacops cristata. 



Dalmanites(Hansmannia) concinnus. 

 Dalmanites( Coronnrus) emarginatus. 

 Dalmanites (Corycephalus) regalis. 

 Dalmanites {Chasmops) anchiops. 

 Dalmanites ( Chasmops) anchiops, var. 

 armatus. 



Dalmanites (Chasmops) anchiops, var. 

 sobrinus. 



Acidaspis callicera. 

 Lichas (Terataspis) grandis. 

 Lichas (Conolichas) hispidus. 

 Proetus Conradi. 

 Proetus angustifrons. 

 Proetus Hesione. 

 Proetus crassimarginatus. 

 Proetus sp. 



Phaethonides arenicolus. 

 Cyphaspis minuscula. 



In addition to these are the species Proetus curvimarginatus and 

 Proetus latimarginatus, from the sandstone beds at Pendleton, 

 Indiana, which lie at the base of the Corniferous limestone, and 

 contain a fauna closely allied to that of the Schoharie grit in the 

 State of New York. 



Gorniferous Limestone. 

 The greatest numerical development of the Devonian Crus- 

 tacea, as a whole, is found in this extensive formation. 

 The species are, however, mostly of Trilobites which here 

 attain their specific and individual culmination, all other 

 orders of Crustacea, excepting the Cirripedia, being 

 unrepresented. The condition of preservation of the fossils is 

 often unsatisfactory, the specimens being generally in a disjointed 

 or fragmentary condition ; moreover the character of the matrix 

 is such that it is often a matter of great difficulty to prepare the 

 specimens in a proper manner for study. When the test of the 

 animal has been silicified the matrix is usually in the same condi- 

 tion, and when preserved in the limestone, the substance of the 

 test is usually softer and more friable than the matrix. The 

 transported boulders of chert which are found abundantly in the 

 drift accumulations south of the lines of outcrop of these rocks, 

 and have become decomposed by the gradual removal of the calcic 

 carbonate mixed with the silica, have proved a very fruitful source 

 of instructive specimens. On account of the usually fragmentary 

 condition of the specimens, a few of the species here described 

 may eventually prove to be founded upon different parts of the 



