152 THE DEVONIAN OF MISSOURI. 



1913. Leplodesma rogersi Clarke and Swartz, Maryland Geol. Surv., Middle and 

 Upper Devonian, pp. 636-637, pi. 63, fig. 3. 



Hall's description — "Shell of small or medium size, sub-rhomboidal; body ovate, 

 very oblique; length greater than the height; anterior and basal margins broadly rounded; 

 posterior margin extended and abruptly recurved. 



Valves equally convex above. Right valve somewhat depressed below, com- 

 paratively higher than the left. 



Hinge line straight, longer than the length of the shell. 



Beaks sub-anterior, obtuse, nearly erect, prominent. Umbonal region gibbous, 

 oblique. 



The anterior extremity is scarcely alate or auriculate, consisting of a rounded 

 extension, straight above and slightly sinuate at the base. Wing comparatively large, 

 triangular, joining the body of the valve near the posterior extremity, defined by the 

 crowding and curving of the concentric striae; margin nearly straight for five-sixths 

 of its extent, then actually recurving; extremity prolonged into a mucronate spine which 

 extends beyond the posterior limit of the valve. In the right valve the wing is less deeply 

 sinuate. 



Test thin, marked by closely arranged concentric striae, which at irregular intervals 

 are crowded into fascicles, producing a gently undulated surface. On the wing the 

 striae are closely arranged, and just below the hinge line are turned backward along the 

 spiniform extension of the wing. 



Interior unknown. Ligamental area narrow, having several fine grooves parallel to 

 the hinge." 



Remarks — Fragments of this species are common in the St. Laurent limestone. 

 With the specimens collected it is impossible to distinguish L. rogeri Hall from L. 

 spinigerum Hall, and the reference is made to the former on the basis of the age of the 

 rocks from which the specimens were collected. 



Occurrence — St. Laurent limestone from three miles south of St. Marys. 



Family Conocardiidae 

 Genus Conocardium Bronn 



Conocardium ohioense Meek 



Description and synonomy on pages 112 and 113. 



Figured on plate 26 



Remarks — Only two specimens from southeastern Missouri are in the Walker 

 Museum collection. They are imperfect but are readily identifiable. 

 Occurrence — Grand Tower limestone of Little Saline Creek. 



Family Pteriidae 

 Genus Actinopteria Hall 



Actinopteria cf. boydi (Conrad) 



Plate 36, figure 6 



1842. Avicula Boydii Conrad, Jour. Acad. Nat. Sci., Phila., vol. 8, p. 237, pi. 12, fig. 4. 

 1884. Actinopteria Boydi Hall, Pal. New York, vol. V, pt. 1, Lamellibranchiata. I, 



pp. 113-116, pi. 19, figs. 2-24, 26-30"; pi. 84, figs. 16, 17. 

 1889. Actinopteria boydi Nettleroth, Kentucky Fossil Shells, pp. 229-230, pi. 3, fig. 2. 

 1909. Actinopteria boydi Grabau and Shimer, North American Index Fossils, I, p. 



449, fig. 592. 



