NO. 2297. BRACHIOPOD GENUS PLATYSTROPHIA—MCEWAN. 429 



are represented by broad, shallow undulations which ])ear the fine 

 striations. 



The lateral slopes of the brachial valve are evenly convex and the 

 fold rises but slightly above the convexity; those of the pedicle 

 valve are convex next to the sinus but become concave toward the 

 cardinal angles. The sinus is almots lacking at the beak, but 

 becomes moderately deep at the front. 



There are three plications in the sinus at tiie beak. Owing to 

 poor preservation the plication pattern is not determinable, but the 

 gi'eater strength of the median plications suggests that it belongs 

 to the Triplicate Type. At a distance of 5 ± mm. from the beak, 

 the plications begin to break up and form a finely striated sinus. 

 The brachial valves were so poorly preserved that little could be 

 determined about the plication pattern of the fold except that it 

 was finely striated. 



Measurements. — 27 mm. along the hinge, 35.5 wide across the 

 middle, and 37 mm. high. 



Occurrence. — Richmond Group. Fernvale limestone: Old Quarry 

 southeast of Regenhardts quarry northwest of Cape Girardeau, 

 Missouri, 



Ootypes.-~C&,i. No. 65872, U.S.N.M. 



C. HIGH FOLD SUBGROUP. 

 PLATYSTROPHIA PROFUNDOSULCATA (Meek). 

 Plate 47, figs. 16-18. 



Orlhis (Platystrophia) laticosla var. profundosulcata (James) Meek, Pal. Ohio, 



vol. 1, 1873, p. 117, pi. 10, figs. 2a-d. 

 Orthis biforata Lesley Geol. Surv. Pennsylvania, Kept. P. 4, 1889, p. 508, 



figs. 2a, 2b. 

 Platystrophia frofundosulcata Foerste, Bull. Sci. Lab. Denison Univ., vol. 16 



1910, p. 58, pi. 6, figs. 15a-c. 

 Platystrophia lynx var. laticosta Cumings (part), 32ncl Ann. Rept. Dept. Geol. 



and Nat. Res. Indiana, 1907, pp. 918, 919. 



PlatystropMa profundosulcata is smaller and more gibbous than 

 Platystrophia laticosta. The sinus is more profound and the fold 

 higher than specimens of that species of the same size. The sinus 

 bends down so rapidly as to truncate the fold before it has reached 

 as far forAvard as in other species of the genus. 



The hinge line is generally shorter than the width across the 

 middle; in rare cases it may slightly exceed it. The slopes of the 

 pedicle valve are convex next to the sinus and strongly concave near 

 the cardinal extremes; those of the brachial valve are convex. They 

 descend rapidly to tlie lateral margin and less rapidly to the frontal 

 margin. 



The strength of the lateral plications of the fold and sinus varies 

 from subequal to mucli weaker than the median plications. Four 



