13 



LIOPTERIA SUBOVATA, n. sp. 



Plate IT, Fig. 7, left valve; pari of the ear broken away; Fig. 8, 

 right valve of another specimen; Fig. 9, left valve 

 of another specimen. 



Species medium size, subrhomboidal. Body obliquely subovate. 

 Anterior margin nearly straight above and abruptly rounded into 

 the basal margin below. Basal margin narrowly rounded. Pos- 

 terior margin somewhat straight above and abruptly rounded into 

 the basal margin below. Hinge line straight from the anterior 

 side of the beak to the posterior extremity, and nearly as long as 

 the shell. Beak of each valve obtuse and situated near the an- 

 terior side of the shell. It is separated from a short ear by an 

 undefined longitudinal sulcus. Both valves are moderately gib- 

 bous, the left valve rather more convex than the right. The pos- 

 terior umbonal slope is rounded and soon merges into the general 

 convexity of the shell. The wing is flat and terminates in a long 

 acute extremity. The shell is marked with concentric lines of 

 growth. 



All of our specimens are casts and the left anterior ear is 

 always injured. No radiating lines are discernable. 



This is a shorter form with a larger wing than L. speciosa, 

 and its general outline will distinguish it from all other species. 



Found by R. A. Blair, in the Chouteau limestone, near Sedalia, 

 Missouri, and now in the collection of S. A. Miller. 



LIOPTERIA SPECIOSA, n. sp. 



Plate II, Fig. 10, left valve, slightly broken anterior to the beak. 



Species rather above medium size, subrhomboidal. Body narrow 

 above and obliquely elongate- ovate. Anterior margin broadly 

 rounded above and abruptly curving into the basal magin below. 

 Posterior margin netrly straight until it rounds into the basal 

 margin. Hinge line straight from the an'erior side of the benk 

 to the posterior extremity and about half the length of the shell. 

 Beak of the left valve obtuse and situated near the anterior end 

 of the shell. It is separated from a short ear by an undefined 

 longitudinal sulcus. The umbonal region is somewhat gibboup, 

 but the greater gibbosity of the valve is in the middle pait. 

 The posterior umbonal slope is subangular above but gradually 



