EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 6 1 



before only in the lower Trenton conglomerate of Rysedorph hill near 

 Albany and definitely indicate not the Trenton fauna normal to the 

 Mississippian province of that time, but the invading fauna from the 

 Atlantic province whose closer affiliations are with European species. 



Two spots in the sea wall have afforded these fossils, one not far from 

 the south end of the cliff where were taken 



Calymmene callicephala Parastrophia hemiplicata 



Dalmanella testudinaria Zygcspira 



Rafinesquina 



These were from calcareous nodules imbedded in the shales. 



The other locality lies just north of the most apparent line of 



displacement where the strata have lost their contortions. Here were 

 obtained 



Tretaspis reticulatus Illaenus americanus 



Ampyx hastatus Pterygometopus cf. intermedins 



Ptychopyge iilrichi 



It is not safe to infer great difference in age of these associations. 



North flank. From the calcareous layers which, with the eroded inter- 

 leaved shales form the outermost northern reach of the strata and are 

 exposed only at low tide as reefs, were obtained a few fossils ; Platyceras, 

 large species of Helderberg type; Zaphrentis corticata Billings; 

 Z. cingulosa Billings. 



The shaly layers on the high vertical north face of the scarp have 



afforded species suggesting the following identifications : 



Hindia sp Leptaena rhomboidalis Wihkens 



Monograptus cf. clintonensis Hall Stropheodonta cf. varistriata Conrad 



Duncanella cf. borealis Nicholson Spirifer cf. niagarensis Conrad 



Streptelasma cf. caliculus Hall Spirifer modestus HalU 



Pleurodictyum cf. lenticulare Hall Cypricardinia af. siiblamellosa Hall 



Dalmanella cf. perelegans Hall Phacops sp. 



Giving special attention to the trilobite in which lies the clearest indi- 

 cation of geologic age, we find it to be a fully developed Phacops such as 

 nowhere occurs in the typical Siluric depos-its of the Mississippian sea or 



