NEW SPECIES OF PALAEOZOIC INVERTEBRATES FROM 

 ILLINOIS AND OTHER STATES. 



BY S. A. MILLER AND \YM. F. E. OURLEY. 



SUBKENGDOM MOLLUSCA. 



CL^SS LAMELLIBRANCHIATA. 

 ORDER SIPHON IDA. 

 FAMILY CARDIID.E. 



LUNULIOARDIUM GRANDE n. sp. 



Plate I, Fig. 1, right valve; Fig. 2, left valve of another spec- 

 imen; Fig. 3, anterior view of same. 



Shell very large, subovate. Valves highly convex or tumid. 

 Height about one- sixth more than the length. Anterior side 

 rounded and recurved toward the basal margin. Posterior and 

 basal margins broadly rounded. Beaks near the middle, prom- 

 inent and incurved over the cardinal line. Umbones gibbous and 

 gradually merged into the convexity of the valves. Thickness 

 through the greatest convexity of the valves about one-sixth less 

 than the greatest length. Surface marked by from seventy to 

 ninety fine radiating plications, that increase in size without divis- 

 ion or implantation, toward the margin of the shell. Our speci- 

 mens are casts but the plications are so distinct, that without 

 careful inspection, one might suppose he was looking at the shell 

 itself. There are some undefined concentric undulations of growth 

 of the shells preserved on the casts. 



This species is so different from any other defined Lunulicar- 

 dinm that no comparison with any of them is necessary. It may 

 not be a Lunulicardium but as the hinge line and interior are 



