BRACHIOPODA—PROTREMATA. 



237 



Fig. 289. a, Chonetes scitulus; b, 

 same, interior of brachial valve, X 2 > 

 d, e, C. lepidus, natural size and enlarged ; 

 c, C. setigerus, X2. (After Hall.) 



124. C. scitulus Hall. (Fig. 289, a-b.) Devonic. 

 Somewhat gibbous, with numerous (50-60) striae near the front 



of the shell and many (10-14) oblique cardinal spines. Interior of 

 brachial valve strongly pustulose. 



Marcellus-Chemung of New York, Pennsylvania, Ohio. 



125. C. setigerus (Hall). (Fig. 

 289, c.) Devonic— Lower 

 Carbonic. 



Moderately convex with three 

 vertical cardinal spines on each 

 side of the beak. 



Marcellus-Waverly of New 

 York, Pennsylvania, Ohio, 

 Michigan, Nevada. 



126. C. lepidus Hall. (Fig. 

 289, d-e.) Devonic. 

 Similar to C. scitulus but is 



smaller, the pedicle valve is 

 more convex, with a mesial sinus and 4 to 10 marginal spines. 

 Marcellus-Chemung of New York and Pennsylvania. 



127. C. aurora Hall. (Fig. 285, e-f.) Devonic-Lower Carbonic . 

 Differs from C. logani in its smaller size (about y inch wide\ 



and shorter hinge line, the hinge line being usually less than the 

 greatest width of the shell. 



Tully-Burlington of New York, Ohio, Iowa, Northwest Territory. 



128. C. logani Norwood and Pratten. (Fig. 285,^--^.) 



Mississippian. 



Pedicle valve quite convex. Greatest width of shell at hinge 

 line (about y 2 inch). Surface marked by 20-40 fine, dichotomiz- 

 ing, radiating lines, crossed by fine concentric striae. 



Kinderhook-Burlington of Ohio, Illinois, Iowa. 



129. C. illinoisensis Worthen. Mississippian. 

 Small (about y 2 inch wide), with five or six oblique spines on 



each side of the beak. Surface marked by 1 00- 1 20 very fine dicho- 

 tomizing striae near the front of the shell. 

 Burlington of Ohio, Indiana, Illinois, Iowa. 



x 30- C. glaber Geinitz. Upper Carbonic. 



Slightly larger than C. mucronatus, thin, transversely subsemi- 



