12 



ville. Young forms of Catazyga were found on Mullet creek in the zone of 

 Strophomena varsensis, which in all probability are the young of C. headi, and 

 it is probable, also, that Townsend procured his specirnens from this zone. 



C. headi is represented in the Cincinnati basin by the variety C. headi 

 schuchertana (Ulrich), which is with difficulty separated from the type species 

 of Canadian localities. According to Foerste, 1 this variety differs in not possess- 

 ing the broad but very shallow median depression along the anterior part. of 

 the pedicle valve, and also in the greater tendency in the Ohio variety toward a 

 subquadrate outline in the case of the brachial valve, at least posteriorly, owing 

 to the considerable lateral extension of the hinge line. Foerste evidently 

 considers these distinctions of little value, as he says: — 



If these features do not prove comparatively constant for the Cincinnatian specimens all 

 attempt to distinguish them under a separate designation may prove of little value. 



C. headi schuchertana occurs in the upper part of the middle or Clarkesville 

 division of the Waynesville and at the base of the Blanchester or upper division, 

 according to Foerste. C. headi occurs in strata correlated with the Waynesville 

 on Manitoulin and at Meaford; in Quebec, in addition to occurring abundantly 

 in Waynesville strata, it ranges for many feet down into rocks which are 

 correlated with the Maysville. 



Hebertella occidentalism Hall. — This is a very abundant species in the Rich- 

 mond of the Credit river. It occurs in all three members although perhaps 

 in greatest abundance at the top of the Meadowvale. H. occidentalis is the 

 only species of brachiopod usually regarded as typically Richmond to be found 

 in the Dundas formation on the Credit river, a few examples being found in the 

 Credit member at Erindale. 



Platystrophia cf. acutilirata (Conrad). — One specimen was selected from a 

 trayful of brachiopods labelled " Platystrophia clarkesvillensis Streetsville," 

 which resembles P. acutilirata more closely. It is more extended along the 

 hinge line than P. clarkesvillensis, and has more numerous lateral plications than 

 the latter. . The exact horizon from which the specimen came is not known. 



Platystrophia clarkesvillensis, Foerste. — This is one of the most abundant 

 species of brachiopods on the Credit river, being found in the Meadowvale, 

 in the Streetsville, and in the upper part of the Erindale members of the Rich- 

 mond. In Ohio, according to Shideler, it is confined to the Waynesville. Its 

 range is thus considerably higher in the Credit River section than in Ohio. 



Rafinesquina alternata, Emmons. — Two forms of R. alternata are found on 

 the Credit river. One of these forms is herein referred to the type, while the 

 other is given the new varietal name R. alternata sub circular is. R. alternata is 

 abundant in the bryozoan reef in the Erindale member and in the rocks 

 immediately overlying the Columnaria reef in the Meadowvale member, but 

 has not yet been found in the Streetsville. No evidence of the presence of 

 either of the forms has yet been obtained from the Dundas formation on the 

 Credit river, although R. alternata is abundant in this formation on the 

 Humber river 



Rafinesquina alternata subcircularis , var. nov. — See page 29. 



'Bull. Sci. Lab. Denison Univ., 16, 1910, p. 32, et seq. 



