In general form this genus most, resembles Edmondia and if we 

 had not found the hinge teeth and hinge line we would have con- 

 tented ourselves by referring the species to that genus. But Ed- 

 mondia has a narrow hinge and no teeth; while this genus has 

 a wide hinge, three teeth and a pit beneath the beak, which sep- 

 arate the genera into distinct families. Edmondia is classed with 

 the Cardiomorphidiv while this genus, by its internal structure, 

 allies itself with radiately ribbed shells and may provisionally be 

 referred to the Cardiida\ The generic name is in honor of the 

 veteran naturalist and collector R. A. Blair, of Sedalia, Missouri. 



BLAIRELLA 8EDALIENSIS, n. sp. 



Plate I, Fig. 4, hinge line; Fig. 5, outer side of the same shell, 



ivliich is eroded; Fig. 6, right valve of a cast; Fig. 7, 



rigid valve of anotlier cast; Fig. 8, Cardi 



nal view oj the same specimen. 



Shell subovate to subcircular. Length from one fifth to one 

 fourth greater than the height. Cardinal line straight, posterior 

 to the beaks, and more than half the length of the shell. An- 

 terior, posterior and basa! margins rounded. The posterior mar- 

 gin a little more acutely rounded than the anterior, and the basal 

 margin more broadly rounded than either of them. Valves regu- 

 larly convex and somewhat gibbous in the umbonal region. Width 

 or thickness through the valves nearly equal to half the greatest 

 length of the shell. Beaks forward of the line of the anterior 

 third, prominent, and incurved over the hinge. Post cardinal and 

 antero-cardinal slopes concave. Shell thick on the cardinal line 

 and at the anterior end. Cardinal line grooved externally for the 

 ligament. Large concave pit beneath the beak of the right valve, 

 anterior to vvhich, there is a long tooth, and posterior, to which, 

 there is a strong bifid tooth. Surface marked by very numerous 

 concentric lines of growth. 



Found by R. A. Blair and also by S. A. Miller, in the Chou- 

 teau limestone, near Sedalia, Missouri, and now in the collection 

 of S. A. Miller. 



