202 



NEW YORK STATE MUSEUM 



extended at the posterolateral margin from which the retreat 

 toward the posterior wing is abruptly oblique. The surface of 

 the left valve is covered by fine radii, equal on the anterior slope 

 but unequal on the posterior and showing a tendency to fascicula- 

 tion. These are minutely cancellated by concentric lines which on 

 the anterior slope and wing and on the posterior slope become 

 prominent to the exclusion of the radii. The right valve is shallow, 

 evenly depressed, with the radii along the crescence line stronger 

 and more distant and the cancellating lines subdued. 



The hinge is distinctly pterineoid, showing a doubly divided um- 

 bonal tooth, strong oblique posterior ridge and broad, striated liga- 

 ment surface. 



This shell, extraordinarily abundant at some localities, is readily 

 recognized by its extremely fine radial surface markings accom- 

 panying unusual size. 



Lozver Dcvonic. Telos lake dam and Moosehead lake, 7 miles 

 north of Kineo, Me. 



Pterinea moneris nov. 



Somewhat oblique valves with hinge line less than the greatest 

 length, anterior beaks, and moderately developed posterior wing. 



i^Bas^^ 



^^ 



Pterinea moneris 



The surface is depressed and entirely devoid of radial markings on 

 either body or wing, thus only concentric lines or rough wrinkles 

 are present. 



