308 PALEONTOLOGY OF OHIO. 



seventh the entire length of the valves behind the anterior extremity; 

 posterior umbonal slopes very oblique, angular at and near the beaks, 

 but becoming more obtuse as they extend obliquely backward and down- 

 ward to the most prominent part of the posterior margin ; flanks below 

 and posterior dorsal regions above the umbonal ridges more or less flat- 

 tened, while in some specimens a very faint impression may be seen 

 extending from each beak obliquely backward and downward below each 

 umbonal slope nearl}^ to the central region of the base (see flg. la, pi. 16). 

 Surface marked with rather distinct concentric lines, and obscure ridges 

 and furrows, crossed sometimes by very obscure traces of radiating lines 

 that are generally quite obsolete on casts, while some specimens show 

 scarcely perceptible indications of two linear radiating ridges, or raised 

 lines on each posterior dorsal region, above the umbonal ridge (see 

 fig. Ic). 



Length of largest specimen seen, about 1.71 inch ; height, 0.70 inch ; 

 .convexity, 0.40 inch. 



Our figures and description are from some of the original typical 



ispecimens of the species, or at least that were labeled and returned to 



.Dr. Newberry, with the name attached, by the author of t^je species. It 



;seems to be related to the last, but differs in the characters mentioned 



in the remarks on that species. 



Locality and position : Our figured specimens are from the Cuyahoga shale (apart 

 .oi theWaverly sandstone series), Medina county, Ohio; it also occurs at the same 

 Jbiorizon at Newark, Ohio. 



Genus PROAIACRUS, Meek, 1871. 



(Am. Jour. Conch., VII, 4.) 



Promackus Andeewsi, Meek. 



Plate 17, figs, la, 6. 

 ' Sanguinolites {Promacrns) Andrewst, Meek, 1871, ib., 7. 



Shell attaining a large size, elongate-subtrapezoidal, the length being 

 ,more than three times the height, moderately convex, with flattened 

 .flanks; posterior margin obliquely truncated from the posterior extrem- 

 ity of the hinge to the base ; basal margin long, nearly straight or but 

 slightly convex in outline; anterior extremity very narrowly rounded; 

 dorsal margin nearly straight and parallel to the base behind the beaks, 

 but declining gently forward with a slightly concave outline in front, 

 where it seems to be inflected so as to form a lanceolate lunule : beaks 



