ILI. Schonarre Grit.—The Cauda-Galli Grit graduates insensibly upwards into a fine- 
grained calcareous sandstone, lithologically not unlike the Oriskany sandstone, and known as 
the ‘‘ Schoharie Grit.” This sandstone is only about four feet in thickness, and is richly fos- 
siliferous. The organic remains are decidedly Devonian in their character, and some of the 
more typical species pass on into the overlying Corniferous limestone without change. As ex- 
amples of such may be mentioned Strophomena demissa, S. Chemwngensis, and S. perplana. 
No representative of the Schoharie Grit has been detected in Canada unless, as previously 
suggested, the so-called Oriskany Sandstone of Western Ontario is truly the equivalent, in part 
if not altogether, of this formation. 
IV. Upper Hetperserc or Cornirerous Limestonn.—The essentially arenaceous 
deposits of the Cffida-Galli Grit and Schoharie Grit are surmounted by the group of calea- 
reous sediments, which may be called “ Upper Helderberg,” from their development in tho 
mountains of this name, or “Corniferous,” from their usually having disseminated through them 
considerable quantities of siliceous matter in the shape of hornstone or chert (Latin cornu, 
horn). In the State of New York these calcareous sediments are divided into two closely re- 
lated groups, of which the lower has a thickness of about twenty feet, and is termed the 
“ Onondaga Limestone ;” whilst the upper is about fifty feet thick, and constitutes the “ Cor- 
niferous Limestone” proper. 
Even in the State of New York the distinction between the Onondaga and Corniferous 
Limestones is one of little moment; and in Canada no such separation can be made. 
In Western Ontario the limestones which represent the Onondaga and Corniferous limestones 
of New York, constitute a single formation indivisible upon either paleontological or lithologi- 
cal grounds, and to this the name of “ Corniferous Limestone” has been generally applied by 
the Canadian geologists, The formation appears in Canada to have a thickness of about one 
hundred and sixty feet, and itis estimated by Sir William Logan to cover an area of probably 
not less than six or seven thousand square miles. It is, however, for the most part deeply 
covered by drift, and is, therefore, but rarely exposed. Throughout almost‘its whole extent, 
it is richly fossiliferous, its organic remains consisting mainly and characteristically of 
corals, there being, however, also numerous Brachiopods, Gasteropods, Polyzoa, Sponges: 
Trilobites, and Crinoids. 
V. Marcetius SHate.—This group consists of a series of black fissile shales, some- 
times with subordinate layers of impure limestone, the whole having a thickness of from fifty 
to one hundred feet. No representative of this group, as distinct from the overlying shales of 
the camilton group, has as yet been satisfactorily determined in Canada. 
VI.—Hamitton Group.—tThis group consists of a series of argillaceous, shaly, or 
flagey beds, with thin courses of limestone, which varies in thickness, in the State of New 
York, from two hundred to as much as twelve hundred feet. In Canada, the Hamilton 
Group is well represented by argillaceous and calcareous shales with intercalated beds of lime- 
stone, the whole having an estimated thickness of about three hundred feet. Though occupy- 
ing a considerable area in Western Ontario, the Hamilton beds are seldom well exposed, and 
they are best exhibited in the Townships of Bosanquet and Plympton. They are charged with 
organic remains, consisting, for the most part, of corals, Brachiopods, and Polyzoa. 
VII. Totty Limesronz.—In the eastern portion of the State of New York the strata 
of the Hamilton Group are surmounted by a dark-blue limestone, about twenty feet in thick- 
