GUELPH FAUNA IN THE STATE OF NEW YORK 5 



phalus, Euomphalus and Polytropis (aucl.) and of schizostomatous genera of 

 the style of Murchisonia, Pleurotomaria, Loxoplocus, etc. These are all 

 often of notable size and are more abundant individually and in species than 

 at any other Siluric date in American sections. (2) Abundance of cephalo- 

 pods of cyrtoceran genera, of Phragmoceras, Trochoceras, etc. (3) Pres- 

 ence and special life period of the heavy- shelled, edentulate brachiopods, 

 Monomerella, Trimerella and Rhinobolus. (4) Immense abundance at 

 certain localities of the ponderous shelled clam Megalomus. (5) Paucity 

 of other lamellibranchs and of brachiopods, bryozoans and trilobites. 

 (6) Existence of corals and coral-making stromatoporoids, for the most 

 part in an incomplete and semimacerated condition. Their abundance in 

 the fauna is unquestionable, but their present condition is no true indica- 

 tion of their original state. 



A fauna of such composition is distinctly late Siluric, at the same time 

 quite as distinctly unlike any other element of the Appalachian Siluric 

 sections. 



The term Guelph, then, indicates both a faunistic and, in its typical 

 province, a lithologic element of distinctive significance in the Siluric suc- 

 cession. In no sense is it a late presentment of the Niagaran fauna as 

 expressed in the shale beds beneath the Lockport limestone. It is true 

 and natural that species of the preceding fauna should present themselves 

 in the Guelph congeries, and though this is not carried to great extent, yet 

 we may always expect to find therein some well known and widespread sur- 

 vivors of the lower fauna. 



GUELPH FAUNA OF NEW YORK AND ITS STRATI- 

 GRAPHIC RELATIONS 



Historical 

 During the construction of the Erie canal, 1817-25, the rock cut- 

 tings near Newark in Wayne county brought to light an impure light 

 colored dolomite. Some fossils were obtained from this rock by Dr G. 

 W. Boyd, assistant to Professor James Hall, geologist in charge of the 



