

BRACHIOPODA—PROTREMATA, 



233 



by lamellae which extend as strong ridges entirely around the 

 large muscular area. Oriskany (Devonic). 



117. H. proximus Vanuxem. (Fig. 283.) Devonic. 



Pedicle valve nearly flat ; its interior^marked by strong muscular 



imprints which occupy a large cardiform space. The imprint of 



Fig. 283. Hipparionyx projcimus. (After Hall.) 



this on the internal mold suggested the name of " horse's hoof." 

 Brachial valve convex; surface marked by fine subequal striae. 

 Oriskany of New York, Pennsylvania, Ontario, etc. 



XLII. Chonetes Fischer de Waldheim. 

 Small. Pedicle valve convex ; brachial concave or flat. Hinge 

 line straight, forming greatest diameter of shell. Hinge areas 

 narrow, that of the pedicle valve bearing a single row of hollow 

 spines on its upper margin. Muscular area of both valves divided 

 by a low median ridge. Cardinal process simple. Surface covered 

 with radiating striae. Siluric-Carbonic. 



