CATARACT FAUNA 285 



hm-{-Bucanopsis trilohata (Conrad). In the Manitoulin and Cabots Head 



members at Hamilton; also In Medina and Clinton. 

 ■\--\-Platy stoma cf. niagarense Hall. Small specimens rare in Manitoulin 



member at Cataract and elsewhere. 

 Osteacoda: 



m.*IsocMUna cylindrica (Hall). This Medina form or a very similar one 



also occurs rarely in the Manitoulin member. 

 Trilobita : 



XCalymene niagarensis Hall? Fragments are common in the Manitoulin 



member. May turn out to be C. vogdesi. 

 XDalmanites, sp. undet." Niagara Gorge. 

 b-{-Encrinurus cf. punctatus Wahlenberg. Fragments of two species of 



Encrinurus occur in the Manitoulin member. 

 XAcidaspis sp. Manitoulin member at Hamilton. 

 XLichas sp. Manitoulin member near Collingwood. 



THE MEDINA FORMATION 



In the second part of this paper the history of the Medina formation 

 is given, and it is there shown that although Vanuxem was the first to 

 use the name in print, the credit rightly belongs to Hall and dates from 

 1840. The name then embraced a great thickness of red sandy shales 

 and some sandstones, constituting the lower and the greater part of the 

 formation, which is terminated by variegated sandstones and shales. 

 This definition of the Medina was retained everywhere until 1905, when 

 Graban split the formation into two series, referring the lower red shales 

 to the Ordovicic as the shore phase of the Eichmondian. Subsequently, 

 in 1908, he named these shales the Queenston (synonym Lewiston, Chad- 

 wick, 1908), retaining the name Medina for the upper sandstones and 

 shales, the only part that had been characterized by fossils. This pro- 

 cedure was altogether correct, for we now know that the Queenston is 

 the easterly and shore phase of the Eichmondian, a fact that can be seen 

 by any one who will take the time to study these deposits from Niagara 

 Falls northwestward to the Manitoulin Islands, at the north end of Lake 

 Huron. In the east not a single fossil is to be had in the entire forma- 

 tion other than the burrows Palceopliycus iortuosum, but gradually more 

 and more appear from the base upward as we proceed to the northwest, 

 until finally the entire red beds have changed through lateral transition 

 into bluish calcareous shales and thin limestone replete with Eichmond- 

 ian fossils. Under these circumstances the Queenston must be separated 

 from the higher sandstones, leaving the latter as the typical expression 

 of the Medina, for at Medina along Oak Orchard Creek one practically 

 sees only these red and white sandstones characterized by the well known 



" Grabau : Loc, cit., 



