GUELPH FAUNA IN THE STATE OF NEW YORK 125 



tical or closely allied to M. mylitta Billings, an undescribed Murchisonia 

 identical with one from Gait, Subulites ventricosa, Pleuroto- 

 maria solarioides?, Loxonema longispira, besides other forms 

 which are closely allied to species of the Guelph limestone. 



Hall had hence clearly recognized the presence of the Niagaran and 

 of the Guelph fauna also in the Racine beds, a conclusion which has been 

 fully verified. 



While Hall worked out the relations of these beds in the west, Billings 1 

 added to the Guelph fossils described by Hall in v. 2, Paleontology of 

 New York, a considerable number of new forms, among them specially 

 the large brachiopods Trimerella and Monomerella cited hitherto as 

 Oboluslike forms, and Logan 2 described the stratigraphic relations of the 

 formation in Canada. As to the relation of the Niagaran and Guelph 

 Sir William remarks in this work : 



In Canada, the Niagara rocks are succeeded by a series of strata, 

 which appear to be wanting in the State of New York. . . 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 character- 

 istic fossils are met with in several localities along the shore. These strata, 

 however, have for the most part the lithologic 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 oblongus, 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 

 formation. 



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 Michigan. 



Hall had noted before this 3 that "at some points on the northern shore 

 of Lake Michigan and elsewhere in the lake region, there occurs a light 



1 Paleozoic Fossils. 1861-65. v - * 

 1 Geol. Canada. 1867. p. 336. 

 s Pal. N. Y. 1859. 3:30. 



