112 NEW YORK STATE MUSEUM 



Conocardium cf. inceptum Hall 



Plate 28, figure 19 



This is a small shell and we have seen only a single internal cast which 

 affords characters justifying- comparison with the specimens provisionally 

 identified with this name from the Oriskany of Becraft mountain.' The 

 surface of the shell bears 13 to 14 plications, an abrupt but not deep anterior 

 slope. Conocardium inceptum was described from the Helder- 

 bergian (New Scotland) beds of Albany count)-, N. Y. The species may 

 also be compared with C . incarceratum of the I )alhousie fauna. 



Locality. Edmunds Hill. 



Camarotoechia dryope Hillings 



Plate 30, figure 1 



Localities. Edmunds Hill. Also in the Grande Greve limestone. 



Camarotoechia sp. 



Plate 30, figure 2 

 .s,v pt 1, p. 170 



Locality. Edmunds Hill. 



Rensselaeria atlantica Clarke 



Plate 29, figures 1-18 



Rensselaeria mainensis Williams. U. S. Geol. Sur. Bui. 165. 1900. p. 80, not 



described or figured 

 Rensselaeria atlantica Clarke. N. Y. State Mus. Bui. 107. March 1907. p. 243 

 Rensselaeria mainensis Williams. U.S. Xat. Mus. Pruc. April 1907. -,2:267 



The Rensselaerias of the Chapman Plantation faunas are of singular 

 interest for the type of structure the)- present. They occur both in the 

 Presque Isle stream outcrops and at Edmunds Hill but there is a difference 

 in the forms from the two localities which is expressible in terms of 

 development only. 



These shells have a subnaviculoid contour, that is, the ventral valve is 

 highly arched and elevated medially, the beak conspicuous and overarching 

 the hinge, the lateral slopes of this valve abrupt while the dorsal valve is 

 but gently convex, its beak being so depressed that it is obscure and the 

 valve has a shouldered appearance on account of the broad regular convexity 

 across the posterior part, from which there is a gentle slope anteriorly. The 

 marginal outline is subcircular. In the more progressed type expressed in 



1 N. Y. Stale Mus. Mem. 3. 1900. p. 37, pi. 4, fig. 21-23. 



2 Hall, Palaeontology of N. Y. 1859. 3 : 491 (not figured). 



