WAVERLY GEOUP SPECIES. 307 



and furrows of growth, with occasional small, obscure concentric wrin- 

 kles that are not regularly arranged. 



Length, 2.13 inches; height, 0.77 inch; convexity, 0.70 inch. 



This species seems to be nearly related to a form from the same rock 

 at Medina, Ohio, specimens of which were loaned by Dr. Newberry to 

 Prof. Hall sometime back, and returned with the name Sanguinolites seolus 

 attached. A careful comparison, however, of good specimens of each 

 shows them to be clearly distinct, the form under consideration being 

 much more convex along the umbonal slopes, which are also more angu- 

 lar. Its beaks likewise differ in being decidedly more nearly terminal 

 and the inflection of its cardinal margin wider. The specimens of S. seolus 

 also show faint traces of two or three very obscure longitudinal ridges 

 above the umbonal angle of each valve, and impressions in casts, of a 

 slight ridge behind the anterior muscular impression, that are not seen 

 in our shell. 



From the little that is now known of the shell that will probably have 

 to be regarded as the type of the genus Sanguinolites, it is impossible to 

 determine whether or not such species as this can be properly referred, 

 to that genus. They seem to agree, however, more nearly with the same 

 than they do with the typical forms of Allorisma, to which they are also 

 related. 



Locality and position : Rushville and Newark, Ohio. Upper part of the Waverly 

 group of the Lower Carboniferous. 



Sanguinolites jeolus, Hall. 



Plate 16, figs, la, b, c. 



Sanguinolites seolus, Hall (1870?), Preliminary Notice of the Lamellibranchiate Shells- 

 of the Ujjper Helderberg, Hamilton and Chemung groups, etc., page 46. 



Shell depressed, sub-ellij^tic, rather compressed, with height equaling 

 about two-fifths the length ; basal margin forming a long, semi-elliptic 

 curve, or sometimes nearly straight along the middle and curving up' 

 gradually at the extremities; dorsal margin behind the beaks, long, sub- 

 parallel to the base, nearly straight, or very slightly convex in outlinej. 

 and abruptly inflected along its entire length so as to form a narrow, 

 lanceolate false area or escutcheon, while in front of the beaks it slopes 

 abruptly forward with a distinctly concave outline to the most promi- 

 nent part of the front margin, which is above the middle and more or 

 less angular, or very narrowly rounded ; beaks small, oblique, compressed, 

 laterally, depressed nearly to the dorsal line, and placed about one- 



