162 PROCEEDINGS OF THE ACADEMY OF 



description, and his figure of a single riglit valve of his Avicula 

 2iarilis (Journ. Acad. Nat. Sci. Philad., vol. 8, pi. xii., fig. 9), the 

 species under consideration would seem to be somewhat nearly 

 allied. It has nearly the same general outline and obliquity, and 

 somewhat similar cars, though its anterior ear is proportionally 

 shorter, and defined by an impressed line extending from the sinus 

 obliquely upward to the beak. Our shell also differs in being 

 very nearly or quite equivalve, instead of having the right valve 

 flat and the left plano-convex. 



I know nothing of the hinge of this shell, and therefore merely 

 refer it provisionally to Aviculopecten. It is rather more oblique 

 than the species of that genus generally are, and possibly it may 

 be found to have the internal characters of Pterinea or Avicula^ 

 and thus have to take the name Pterinea Sandusky ensis or Avi- 

 cula Sanduskyensis. 



Locality ay\d position. Sandusky and Delaware, Ohio. Corni- 

 ferous group of the Devonian series. 



PTEEINEA (PTERONITEST) NEW ARKENSIS, Meek. 



Shell small, longitudinally subovate or truncato-semiovate, 

 about two-thirds as wide (high) as long, being wide behind and 

 narrowing anteriorly ; cardinal margin straight or slightly curved 

 in outline behind the beaks, and about two-thirds the length of 

 the valves, very short and declining in front of the beaks; poste- 

 rior margin truncated so as to iutersect the hinge at an angle of 

 about 100°, but rounding regularly into the base; anterior side 

 very short, somewhat lobed and narrowly rounded; basal margin 

 semiovate, being most prominent, and ascending obliquely with a 

 very slight!}^ sinuous outline before. Left valve moderately con- 

 vex, the greatest convexity being near the middle, or a little be- 

 fore it, and thence obliquely forward and upward to the beak, as 

 well as downward to the most prominent part of the base behind 

 the middle ; beak xery oblique, elevated a little above the hinge 

 margin, and placed about one-fifth the length of the valve from 

 the anterior extremity; swell of the oblique umbonal and central 

 regions separated from the slightly lobed, narrowly rounded an- 

 terior extremity by a broad undefined impression extending to the 

 antero-basal margin ; posterior dorsal margin compressed and 

 somewhat alate: surface apparently smooth, excepting some very 

 faint ridges of growth, which are most strongly defined on the 



[August 15, 



