50 



appearance. This layer is filled with Strophomena planumbona erindalensis . 

 Strophomena varsensis is also common, as well as young forms of Catazyga headi. 



In addition to the fossils already mentioned, the following species occur 

 rather abundantly in the limestone of the zone. Hallopora onealli creditensis, 

 Hebertella occidentalis , Rafinesquina alter nata, and Rafinesquina alternata sub- 

 circularis. 



There seems to be very little doubt that the rocks of the above zone represent 

 a time equivalent to the Waynesville of the Cincinnati basin. Foerste first 

 found Strophomena varsensis in the Cincinnatian area east of Ottawa and has 

 recorded it in an unpublished manuscript on the fossils of that area. He states 

 that the nearest approach to this species can be seen in the Blanchester division 

 of the Waynesville of Ohio. The variety Strophomena planumbona erindalensis 

 differs only slightly from the type form of the species from the Waynesville 

 of Ohio, and Catazyga headi of the Erindale member is also represented in that 

 state by the variety Catazyga headi schuchertana. 



Upper Erindale. — Above the zone of Strophomena varsensis , the rocks 

 greatly resemble those of the lower members of the Dundas formation as seen 

 at Toronto. Limestone layers are few and far between, and the fossils are less 

 abundant than in the lower part and are of less determinative value. 



The fauna is made up of long-ranging forms, such as Whiteavesia pholadi- 

 f or mis, Pterinea demissa, Byssonychia radiata, and Modiolopsis concentrica, 

 mingled with a few other species which are characteristic of the Richmond as 

 a whole, but which are of very little use in more detailed correlation, such as 

 Homotrypella hospitalis, Hebertella occidentalis , and Rafinesquina alternata 

 subcircularis . Only two species typical of the Waynesville are present, Stig- 

 matella crenidata and Platystrophia clarkesvillensis, and of these the former is 

 represented on the Humber by a form which was described as S. crenulata by 

 Parks and Dyer but which more correctly should be known as a variety of S. 

 crenulata. Platystrophia clarkesvillensis on the Credit river ranges up into the 

 Meadowvale member. 



Correlation. — While the relationships of the Erindale are with the Waynes- 

 ville of Ohio and Indiana, nevertheless great differences are noticed. Many of 

 the most characteristic Cincinnati forms have not been found on the Credit, such 

 as Dalmanella meeki, which gave the original name "Dalmanella meeki zone" to 

 the Waynesville, Hebertella insculpta, Protarea vetusta, Streptelasma divaricans, 

 Rhynchotrema dentata, and Batostoma prosseri. In addition, five new species of 

 Bryozoa and one new species of Brachiopoda are found on the Credit, and one 

 brachiopod shows varietal differences from a related Ohio form. 



Streetsville Member 



Zone of Ischyrodonta miseneri. — The lower beds of the Streetsville member 

 (from the 475- to the 480-foot levels) consist of argillaceous limestone, varying 

 from six to 18 inches in thickness, separated by narrower bands of shale, and 

 characterized by the occurrence of Ischyrodonta miseneri and Byssonychia 

 robusta. The following fossils also occur: Hebertella occidentalis, Platystrophia 

 clarkesvillensis, Byssonychia grandis, Ortonella cf. hainesi, Opisthoptera fissicosta, 

 and Bellerophon cf. mohri. 



Zone of Homotrypa streetsvillensis. — From the 480- to the 489-foot level, 

 the rocks are still calcareous; and at the 483-foot level, there is a massive bed 

 of limestone, 18 inches to two feet in thickness, which can be followed for some 

 distance down the river and which was of use in the determination of the dip 



