Monograph of the Lamcllihrancldata. 219. 



extremity more or less angular in outline; basal margin rounding and 

 ascending obliquely forward from the posterior basal angle ; anterior 

 side extremely short, or with its margin descending and curving back" . 

 ward into the base from immediately in front of the beaks; hinge line 

 short, and a little inflected, so as to form a kind of small area or 

 escutcheon behind the beaks ; beaks prominent, rather oblique, nearly 

 terminal, strongly incurved or subspiral, and distinctly compressed 

 anterio-posteriorly. so as to be sharply keeled on top, the keel being 

 continued as a less angular iimbonal ridge backward and downward to 

 the posterior basal extremity; flanks in front of the umbonal ridge 

 evenly convex, Avhile the space above and behind it, near the beaks, is 

 somewhat concave. Surface only shov,'iug obscure traces of lines of 

 growth. (Hinge and interior unknown.) 



Length, measuring obliquely from the posterior basal angle to the 

 most prominent part of^the umbonal keels, 0*65 inch ; anterio-posterior 

 diameter, measuring parallel to the hinge line (the specimen being 

 defective behind), 0*40 inch; convexity of the united valves, 0*50 

 inch ; length of hinge about 0'30 inch. 



Found near the top of the hills back of Cincinnati. Range un- 

 known. 



Sedgwickiaf fragllis — (Meek). 



« 

 Shell rather small, apparently very thin, longitudinally oblong or 



suboval, rather distinctly convex along the umbonal slopes from the 

 beaks toward the posterior basal margin, and down near the anterior 

 side, while just under the beaks a rather strongly marked impression 

 descends, widening and deepening as it approaches the base; basal 

 margin subparallel in its general outline to the dorsal, but diverging 

 more or less j^osteriorly, where it is most prominent, while it is rather 

 distinctly sinuous toward the front ; posterior margin wider than the an- 

 terior, and more or less truncated; anterior extremity very short, and 

 rounded, or somewhat truncated; hinge line straight, and shorter than 

 the entire length of the valves, apparently very slightly inflected behind 

 the beaks, which are raised a little above the cardinal margin, incurved, 

 contiguous, flattened on the outer sides, and placed near the antei'ior 

 end, with a slight forward inclination. Surface ornamented with mod- 

 erately distinct lines, and irregular minute wrinkles of growth. 



Found at the quarries back of Cincinnati, about 350 feet above low 

 water-mark. Range unknown. 



o^ 



Sedgivickia f coin2)ressa — (IVIeek) . 

 Shell longitudinally oval, compressed, about one fourth longer than 



