308 EIGHTEENTH REPORT ON THE STATE CABINET. 



In the Geology of Canada, published in 1863, the Guelph limestones 

 are described as constituting a distinct formation ; but Sir W. E. Logan 

 remarks : 



"It has already been stated that the strata seen near the mouth 

 of the Riviere aux Sables, at Chief's point, probably strike along the 

 coast by Lyell island to Cape Hurd, and belong in part to the Niagara 

 formation, whose characteristic fossils are met with in several localities 

 along the shore. These strata, however, have for the most part the litho- 

 logical characters of the Guelph formation, and some of their undescribed 

 species of Murchisonia have a strong resemblance to others found in this 

 series. The Pleurotomaria huronensis^ which belongs to the Guelph rocks, 

 occurs on Lyell island associated with Pentamerus ollongus and other 

 characteristic Niagara species ; so that it is not impossible that some of 

 the strata along this coast may constitute a passage between the Niagara 

 and Guelph formations. 



" The Guelph formation appears to be absent from the State of New- 

 York ; and in Canada it probably has the form of a great lenticular mass, 

 the limit of which between Niagara and Guelph is uncertain, though it 

 appears to extend beyond Ancaster. In the other direction, it seems to 

 thin out in Lake Huron, before reaching the northern peninsula of Michi- 

 gan." 



I should not omit to say here, that so far as my investigations have ex- 

 tended on the islands of Lake Huron and Lake Michigan, with the penin- 

 sula between the latter and Green Bay, I have found the presence of the 

 lower portions of the Niagara group, with the general absence of the higher 

 beds. At the same time, along this great extent few fossils occur except 

 Pentamerus ohlongus^ Halysites catenulatus^ and two species of Favo- 

 siTES, with some other corals ; and it is only on continuing the observa- 

 tions to the southward in Wisconsin, that we find a larger number of the 

 Niagara species proper. This indication of beds of passage, pointed out 

 by Sir W. E. Logan, will, I presume, be found in all or nearly all locali- 

 ties where a junction of the two formations can be seen. 



II. DESCRIPTIONS OF SOME NEW FOSSILS FROM THE NIAGARA GROUP. 



In the Report of Progress of the Geological Survey of Wisconsin for 

 I860,* I described several species of Crinoidea, two Cystideans, several 

 species of Brachiopoda, Gasteropoda and Cephalopoda, from the lime- 

 stones of Racine and Waukesha ; leaving a considerable number of species 

 undescribed for want of satisfactory material. It has not been in my 

 power to make such collections as I then anticipated ; and the following 



•Report of the Superintendent of the Geol. Survey, Legislative Documents. 1861. 

 4 



