168 PROCEEDINGS OF THE ACADEMY OP 



to be the usual form of the same, bis tj^pical specimen baving tbe 

 beaks more prominent and fartber removed from the anterior end 

 than in tbe more normal form of tbe species, and its dorsal out- 

 line straigbter and more sloping posteriorl3% with the valves more 

 compressed. Compared with specimens that I have referred to, 

 A. clavata from tlie Chester group of "West Virginia, collected by 

 Prof. Stevenson, our Waverley species are found to agree very 

 nearly with some individuals of tbe latter, though it alwaj'S has 

 its ridges of growth less strongly defined and more irregular, and 

 its anterior basal margin usually more oblique. It also differs in 

 the possession of an anterior umbonal ridge extending from the 

 beaks obliquely backward and downward nearly or quite to the 

 basal margin a little in advance of tbe middle. 



The specific name is given in honor of Prof, A. Winchell, the 

 able State geologist of Michigan, who has described many fossils 

 from tbe same horizon in tbe western States. 



Locality and position. Rushville and Xewark, Ohio. Upper 

 part of the Waverley group of the Lower Carboniferous. 



ALLORISMA VENTRIOSA, Meek. 



Shell subovate, the length being about once and a half the 

 height, moderately convex ; posterior margin obliquely subtrun- 

 cated above, and narrowlj^ rounded or subangular near the middle^ 

 thence sloping obliquely under and forward ; base rather deeply 

 and somewhat irregularly rounded, tbe most prominent part being 

 near tbe middle; anterior side short, with an oblique truncate or 

 concave forward slope above, to the lower extremity of tbe lunule, 

 where there is a more or less angular projection, below which the 

 margin slopes with a slightly convex outline oblique backward 

 and downward sometimes nearly to the middle of tbe base ; dor- 

 sal margin more or less concave in outline, and showing tbe usual 

 lanceolate escutcheon margined on each side b3^a subangular ridge ; 

 hinge equalling about two-thirds the length of the valves; lunule 

 rather small, deep, well defined, and narrow-subovate in form; 

 beaks moderately prominent, oblique, and placed about one- 

 seventh the length of the valves from the anterior end. Surface 

 ornamented by small irregular ridges and furrows of growth. 



Length, 1.46 inches; height to cardinal margin, 0.98 inch; do. 

 to horizon of beaks, 1.03 inches; convexity, 0.66 inch ; length of 



[August 15, 



