BRACHIOPODA—PROTREMATA. 



217 





82. S. inaequistriata (Conrad). (Fig. 262.) Devonic. 



Small. Pedicle valve quite convex. Hinge line extended with 

 acute and sometimes auriculate extremities. Surface marked by- 

 distant striae with fine, almost invisible striae between. 



Onondaga-Hamilton of New York, Kentucky, Indiana, Wiscon- 

 sin, Ontario. 





FlG. 260. Stropheodonta hemispherica. 



83. S. COStata Owen. Devonic. 

 Small (hardly y% inch in diameter). Pedicle valve slightly con- 

 vex ; brachial valve nearly flat. Surface covered with about 

 eleven prominent plications. 



Hamilton of Iowa, Michigan. 



84. S. demissa (Conrad). (Fig. 263.) Middle and Upper Devonic. 

 Length and width nearly equal. Pedicle valve strongly convex. 



Surface striae numerous, strongest and most elevated near the beak 

 and increasing by intercalation and bifurcation toward the 

 front. 



Widely distributed throughout North America, especially in 

 Hamilton group. 



85. S. (Leptostrophia) perplana (Conrad). (Fig. 264.) Devonic. 

 Thin, slightly convex, often almost flat. Extremities of hinge 



line usually prolonged. Surface covered with fine and nearly 

 equal striae, crenulated by fine concentric striae. Differs from 5. 

 conugata in its finer and less prominent striae and in the absence 

 of folds on the hinge margin. 



