206 THE DEVONIAN OF MISSOURI. 



Order Teleodesmacea 



Superfamily Cypricardiacea 



Family Pleurophoridae 



Genus Cypricardinia Hall 



Cypricardinia distincta Billings? 



Plate 54, figure 9 



Cypricardinia distincta Billings, 1874, Pal Fossils, vol. II, pt. I, p. 56, figs. 26, 27. 

 Cypricardinia distincta Clarke, 1908, N. Y. State Mus., Mem. 9, pt. I, p. 157, pi. 24, figs. 



12-19. 



Description — "Under this name the author cited and illustrated the two extremes 

 of variation in this species, one elongate with broad and few growth bands and the 

 umbonal ridge suppressed probably by compression, the other more rhomboidal in out- 

 line, with narrower, more numerous growth bands, sharper umbonal ridge and more 

 sinuous postlateral margin In the absence of intermediate forms these might be re- 

 garded so unlike as to be terms of parallel rather than continuous series. 



" 'Original description — Shell oblong or irregularly ovate; compressed or moderately 

 convex; an oblique, obscure angulation extending from the. umbones to the posterior 

 angle; umbones sometimes slightly flattened by an obscure depression which descends, 

 gradually widening, to the ventral margin; beak small, closely incurved. Dorsal margin 

 straight, slightly concave or convex, parallel with the ventral margin or a little elevated 

 posteriorly, usually about one-fourth shorter than the total length. Ventral margin 

 usually gently concave, but sometimes straight or slightly convex. Anterior extremity 

 usually with the lower half a little projecting and rounded, concave, at the mid-hight 

 or obtusely rounded; posterior extremity, with the most projecting point at the mid- 

 hight or a little below, narrowly rounded or angular; the upper half obliquely truncated 

 with a straight or gently convex slope. 



" "The largest specimen collected is seventeen lines in length, eight lines in height 

 at the umbones, and nine lines high at the posterior end of the hinge line. All the others 

 are shorter and proportionally higher. In several specimens which have both valves 

 in connection, the right valve is the most convex.' 



"The surface of the broad growth rings is usually marked by very fine concentric 

 lines and with good preservation the umbonal slope presents a series of fine radial and 

 interesting surface lines which are sometimes exhibited from the hinge line as far as the 

 middle of the basal margin. Cypricardinia distincta is one of the largest forms of the 

 genus and is unlike the species known to us from the Oriskany fauna. It approaches 

 more nearly the species C. sublamellose and C. carassa Hall of the New Scotland (Helder- 

 bergian) beds of New York. We find these shells to be quite common in the limestones 

 [Grande Greve]."— Clarke, 1908. 



Remarks — This form is possibly represented by an incomplete left valve. 



