13 



Rafinesquina mucronata torontonensis, Parks and Dyer. — This brachiopod 

 is very abundant in the Humber member on the Credit river, where it occurs 

 in limestone in association with Zygospira erratica. It does not differ from the 

 form described by Parks and Dyer from the Humber River section. 



Strophomena planumbona erindalensis , var. nov. — See page 30. 



Strophomena varsensis, sp. nov. — See page 31. 



Trematis millepunctata, Hall. — This species has been found in all formations 

 of the Cincinnatian series in the United States and Canada, from the Eden to 

 the Richmond. A single fragment only was found on the Credit river, in the 

 zone of Strophomena varsensis in the Erindale member of the Richmond, but 

 this fragment shows the ornamentation characteristic of the species so clearly 

 that there can be no mistake about its identity. 



Zygospira (?) erratica (Hall). — This species is found in great abundance in 

 the Humber formation in the quarry at Port Credit, in association with 

 Rafinesquina mucronata torontonensis, Parks and Dyer. These two forms are 

 also abundant on the Humber river at Weston and Lambton. Z. erratica forms 

 one of the connecting links between the Dundas formation of Toronto and the 

 Lorraine of New York, being common to these two formations but absent 

 from the Cincinnatian rocks of the Ohio valley. 



Zygospira modesta, Hall. — This is the most abundant brachiopod on the 

 Credit river, being found in the Dundas formation and in all the members of the 

 Richmond except the Queenston. It is a long-ranging form and, therefore,, is of 

 little use for purposes of correlation. 



Pelecypoda 



Anoptera cf. miseneri, Ulrich. — The exterior of a left valve of a pelecypod 

 was found at the foot of the cliff on the Credit river opposite the Streetsville 

 fair grounds. It is either from the upper part of the Erindale or lower part of the 

 Streetsville member, these portions of the two members being exposed at this 

 locality. The outline of the shell and the character of the plications are like A. 

 miseneri, but as no interiors have been seen and since the horizon at which the 

 species occurs in the Ohio valley (Elkhorn) is much higher than on the Credit,, 

 it is thought best not to refer the shell definitely to this species. 



Byssonychia grandis, Ulrich. — This species occurs in the Streetsville member 

 of the Richmond formation. In Ohio, according to Shideler, it occurs at a 

 somewhat higher horizon than it does on the Credit, namely, in the Saluda and 

 Whitewater divisions. 



Byssonychia radiata (Hall). — This is not a very common species on the 

 Credit river, but typical specimens do occur at various horizons, namely, in 

 the Humber and Credit members of the Dundas formation and in the Erindale 

 and Streetsville members of the Richmond. 



Byssonychia robusta, Miller. — Beautifully preserved examples of B. robusta, 

 of the Whitewater and Saluda members of the Richmond of Ohio, are found in 

 the zone of Ischyrodonta miseneri in the Streetsville member on the Credit river. 

 Byssonychia robusta and B. richmondensis , Ulrich, are very similar and occur 

 at the same horizon in the Cincinnati basin. The ribs are coarser in the former 

 species, varying, according to Foerste, from 38 to 41 in number, while in the 



