BRAGHIOPODA. 137 



Genus Tropidoleptus Hall 



Tropidoleptus carinatus (Conrad) 



Plate 33, figures 11 and 12 



1839. Strophomena carinata Conrad, Third Ann. Rep., N. Y. Geol. Survey, p. 64 

 1867. Tropidoleptus carinatus Hall, Pal. New York, IV, pp. 407-408, pi. 62, figs. 2, 3. 

 1897. Tropidoleptus carinatus Schuchert, Bull. U. S. Geol. Surv. 87, pp. 457-458. 

 1903. Tropidoleptus carinatus Weller, Geol. Survey New Jersey, vol. 3, pp. 381-382, 



pi. 53, fig. 2. 

 1909. Tropidoleptus carinatus Grabau and Shimer, North American Index Fossils, I 



p. 305, fig. 382. 

 1913. Tropidoleptus carinatus Clarke and Swartz, Maryland Geol. Surv., Middle and 

 Upper Devonian, pp. 585-586, pi. 55, figs. 1-5. 



Hall's description — "Shell concavo-convex, semi : elliptical, the length sometimes 

 nearly equalling the width ; hinge line equalling, greater, or less than the width of the shell 

 and the cardinal extremities sometimes rounded so as to give the shell a broadly oval 

 form; the sides are sometimes nearly straight, and the front broadly rounded. 



Ventral valve convex, broadly subcarinate along the middle, and sloping in a 

 flattened curve to the lateral margins and front, which is sometimes slightly truncate or 

 emarginate; cardinal extremities deflected, abruptly incurved at the umbo, and the 

 apex often imperfect from the encroachments of the foramen. Area from half a line 

 to about one line in width; its margins parallel to near the extremities, where it slopes 

 suddenly down from the outer margin. The area is longitudinally striate, and indented 

 by a very wide foramen. 



Dorsal valve moderately concave, sometimes nearly flat, often with a median de- 

 pression or sinus which becomes conspicuous below the middle of the valve; apex small, 

 projecting a little beyond the hinge line. There is a narrow area, interrupted in the 

 middle by a wide pseudo-deltidium which covers the extremity of the cardinal process. 



Surface marked by about eighteen to twenty broad, simple, rounded plications which 

 are wider than the spaces between them ; the central one on the ventral valve is broader 

 and more elevated than the others, while there is a corresponding wider and deeper 

 depression in the middle of the dorsal valve. In rare instances, the plications are 

 bifurcated. Fine undulating concentric striae cover the surface, and a few stronger 

 imbricating lamellae mark the form of the shell in its stages of growth." 



Remarks — No well preserved specimens of this species, from southeast Missouri, 

 are in the collections of Walker Museum or the University of Missouri. Fragments are 

 common and well enough preserved to make the identification positive. 



Occurrence — St. Laurent limestone of Little Saline Creek, Ste. Genevieve County, 



Genus Schuchertella Girty 

 Schuchertella chemungensis pectinacea (Hall) 

 Plate 32, figures 6 and 7 



1687. Streptorhynchus chemungensis pectinacea Hall, Pal. New York, IV, pp. 73-75, 



pi. 10. 

 1897. Orthothetes chemungensis Schuchert, Bull. U. S. Geol. Surv., 87, pp. 295-296. 



Hall's description — "Shells usually symmetrical, often unsymmetrical, semioval, 

 with the hinge-extremities sometimes a little salient, often truncate and sometimes 

 rounded. 



The dorsal valve is moderately convex, or sometimes gibbous. The surface is 

 marked by distant, very prominent striae, with two or three finer ones between them. 

 The hinge, and other features of the shell, are the same as in other varieties of the species. 



