No. 50.] 
453 
Rochester Shale. 
2d Green Shale. 
Pentamerus Limestone. 
Green Shale and iron ore. 
Medina Sandstone. 
Wenlock Shale. 
Caradoc Sandstone. 
The following series exhibits the rocks of the 4th District in their 
order of succession, together with the names of a few of the most com- 
mon and characteristic fossils. The list of fossils will be greatly in- 
creased when we succeed in ascertaining the names of species. 
Old Red Sandstone. 
Chemung Group. f 
Portage Group. 
Gardeau Flagstones. 
Ithaca Group. 
Cashaqua Shale and 
Sandstone. 
Upper Black Shale. 
Tully Limestone. | Atrypha 
Moscow Shale. 
\ Holoptychus Nobilissimus, Sauritolepis Tay- 
> lori.* Fragments of teeth and bones of other 
) fishes, probably the Megalicthys. 
A large Avicula is the characteristic fossil of 
many locahties — Pterinea,Leptaena, Delthy- 
ris, Orbicula, three species, Tentaculites 
tenuis ; several coraUine fossils. 
\ Goniatite, rarely ; Fucoides, vertical to the 
> strata. The fucoid is the characteristic fos- 
) sil. 
^ Fucoides, arranged in short, rigid fragments, 
I on the under side of the strata — seen on the 
j surface of flagstones in many places. Other 
J species of fucoides. 
> Orthis, Leptaena, Delthyris, species undeter- 
) mined ; Fossil ferns. 
> A large Avicula, Goniatite, Posidonia, Cri- 
> noidal joints, &c. 
) Posidonia lirata ; Lingula, two species ; Or- 
) this, Orbicula. 
few fossils. 
Encrinal hmestone. 
J Calymene bufo, Cryphaeus calliteles, Homo- 
> nolotus — , Atrypha affinis, A. prisca, Del- 
) thyris, several species. 
> Asaphus, (new species,) Avicula reticulata,(?) 
> Crinoidal columns of great size. 
* I have proposed the specific name of what I suppose to be an undescribed species 
and genus of a fossil Sauroid fish, in honor of Mr. R. C. Taylor, of Philadelphia, 
who first described the sandstone of Blossburgh, and suggested its analogy to the Old 
Red Sandstone of England. 
t This group requires subdivision before it can be accurately described. 
