438 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



indisputable specimen of fish-remains (Asterolepis). x\ll this taken 

 together, according to Hall and De Verneuil (Sill. Journ. vii. 320, 

 n. s.), permits us to place Oriskany Sandstone on the same horizon 

 with the Rhenish Spirifer-Sandstein of Sandberger, — that is, at the 

 base of the Devonian system (Murchison, Siluria, p. 373). 



Onondaga and Corniferous Limestones. Group II . — These closely- 

 connected strata are severed abruptly from the subjacent grits. Their 

 lithology requires no further notice than to state, that the latter is 

 marked by the great quantity of silica it contains, both infiltrated 

 and in layers. 



Onondaga Limestone presents us with twenty-seven original and 

 twenty-two typical fossils. This includes twelve species of zoophytes ; 

 four of them having ascended from the Niagara section. It is often 

 a true coral-reef. 



The Corniferous Limestone has but one zoophyte, but has nineteen 

 original brachiopods and twenty-two typical fossils in seven genera. 

 Group II. therefore comprehends two independent epochal centres 

 of life. 



Marcellus Shale, Hamilton Rocks, Tully Limestone, and Genesee 

 Slate. Group III. — Marcellus Shale acquires a distinct position by 

 holding the earliest American Goniatites (G. expansus, G. Marcellen- 

 sis), as well as by its eighteen typical fossils. But in the ' Synoptical 

 View ' this shale has been shown to be simply the lower part of the 

 richly fossiliferous Hamilton section. 



This last-named formation has 119 original organisms, and its 

 typical forms amount to the great number of 106 ; they are princi- 

 pally Brachiopoda and Lamellibranchiata. It gives us the charac- 

 teristic fossil, Goniatites punctatus, and the first Inoceramus (ovi- 

 formis). Tully Limestone is a thin stratum, which must have been 

 noticed for industrial purposes, as it is only a slender aggregation of 

 the calcareous matters which often pervade the Hamilton section. 



Genesee Slate is poor in fossils, with but four typical Brachiopoda. 

 There are reasons indeed why it should be rather united to the next 

 succeeding group. 



Portage and Chemung Rocks. Group IV. — These sandstones and 

 shales are the product of the same epoch, and, according to H. D. 

 Rogers, ought never to have been separated. In their fossil contents, 

 however, they are distinct. Of the nineteen original Portage species, 

 only two enter the Chemung — one of these being Clymenia compla- 

 nata ? With the older groups just reviewed, the Portage has very 

 slight connexion. 



The Chemung assemblage of strata are placed apart from all others 

 by the presence of sixty typical fossils, having, at the same time, 

 sixty-eight which are original. They are almost wholly Brachiopoda 

 and Monomyaria, as in the Hamilton section, with which the affini- 

 ties of the Chemung rocks, both lithological and vital, are very strong, 

 although separated by three sections of strata. 



The Catskill Strata. Group V. — This is distinguished at once 

 from its predecessors by the instant arrest of molluscan life, and the 

 presence of Holoptychius nobilissimus and other Old Red Sandstone 



