EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 79 



Rensselaeria ovoides (Eaton) 



Plate 17, figures 10-12 

 See pt 1, p. 164 



The examples of this species have an expression common in smaller 

 New York shells but approach the elongated narrow form of the var. gas- 

 pen si s found in the Grande Greve limestones and Gaspe sandstones. 



Localities. Loose at Cunningham's camp and at foot of Matagamon 

 mountain. 



Rensselaeria cf. stewarti Clarke 



Plate 18, figures 1-3 



See p. 38 



Another shell occurring at a different locality than the others seems to 

 pertain to a distinct species so similar to that cited as to justify a provi- 

 sional reference thereto. This is a persistently small shell with plications 

 varying from 40 to 60 on each valve and has what the others do not possess, 

 a well developed hinge plate and some evidence of ventral muscular scars. 



Locality. Moosehead lake, north of Soccatean point. 



Rensselaeria callida Clarke 



Pkite 17, figures 13-17 



Rensselaeria callida Clarke. N. Y. State Mus. Bui. 107. 1907. p. 241 



On other pages we have entered into some discussion of the species of 

 Rensselaeria of Trigerialike form occurring in Aroostook count)- and at 

 Dalhousie and have indicated their affinities with the Coblentzian species 

 R . strigiceps ami R . crassicosta. We have before us now exten- 

 sive representations of two additional species occurring in association which, 

 while presenting some aspects of similarity to the species referred to (R. 

 atlantica and R . stewarti), are not in full agreement with them. One 

 of these here designated as R. callida occurs in various stages of 

 growth but the adult form is of considerable size, attaining a length of 50 

 mm and upward. Its valves are full, convex with a tendency to gibbosity, 

 the ventral valve being broadly and faintly keeled and the dorsal valve 

 slightly flattened medially, the ventral umbo elevated and arching but not 

 incurving over the other. The outline is quite regularly oval. Beneath 

 the beak the incurvature shows no evidence of flattening into a cardinal 

 area as in the species cited nor is there evidence of such area on the dorsal 

 valve. There are a well defined foraminal opening and tube and the dental 

 plates are considerably developed extending from one fourth to one filth 

 the length of the valve though without thickening. There is no impressed 

 muscular scar and no thickening of the shells in the umbonal region. In 

 the dorsal valve, though there is a median septum extending about one third 



