SPIRIFER 349 



Remarks. This is one of the species which has never previously been 

 illustrated, and which has not commonly been recognized. The type spec- 

 imens have been lost, but the shells here referred to the species agree 

 well with the original definition and occur in the St. Louis limestone, 

 from which formation the types of the species were reported. The species 

 resembles S. bifurcatus as closely as any other, but may be distinguished 

 by its much less angular plications. It differs from S. pellaensis in its 

 shorter hinge-line, rounded cardinal extremities, and in its stronger pli- 

 cations, especially the stronger median plication of the mesial sinus. 



Horizon.- St. Louis limestone. 



SPIRIFER MARSH ALLENSIS n. sp. 

 Plate L, Figs. 13-14 



Description. Shell small, wider than long, the hinge-line shorter than 

 the greatest width of the shell, the cardinal extremities rounded. The 

 dimensions of a brachial valve are : length 12 mm., width 18 mm., length 

 of hinge-line 14 mm., convexity 6 mm. The pedicle valve not known. 



Brachial valve transversely subelliptical in outline, moderately convex, 

 the greatest convexity near the middle, subcarinate along the median line, 

 the umbonal region slightly produced beyond the hinge-line ; mesial fold 

 defined to the beak, scarcely elevated in the umbonal region, becoming 

 moderately elevated anteriorly but not sharply differentiated from the 

 general convexity of the valve, it is rounded in contour and is marked 

 anteriorly by four obscure plications which unite into a single one in 

 passing to the beak; lateral slopes convex antero-posteriorly, the curva- 

 ture a little more abrupt to the cardinal margin, the slope from the middle 

 of the mesial fold to the lateral margin at the widest part of the shell is 

 very slightly convex or is nearly a straight line, giving the valve its sub- 

 carinate aspect, the surface is slightly compressed towards the cardinal 

 extremities, each slope marked by 9 or 10 simple, depressed, rounded 

 plications separated by rounded furrows about equaling the plications 

 in width. 



The minute surface markings of the specimens examined are not per- 

 fectly preserved, but the shell is apparently granulose. rio concentric or 

 radiating stria; of any sort are indicated. 



Remarks. In size and general form this species resembles 8. orestes 

 H. and W., from the Upper Devonian of Rockford, Iowa, but it may be 

 distinguished by its less elevated and less angular median fold and by 

 the more rounded cardinal extremities. 



Horizon. Kinderhook. 



