302 NORTH AMERICAN INDEX FOSSILS. 



294. C. rectirostris Hall. (Fig. 375, d-e.) Devonic. 

 Distinguished from C . plamrostris by its more elongate form and 



extended and attenuate beak. 



Hamilton of New York, Kentucky, Indiana. 



XC. Dielasma King. 



Terebratuloid. Pedicle valve with a large foramen. Brachial 

 valve with a large, anteriorly acuminate hinge plate (muscular 

 platform) raised but little above the bottom of the valve and some- 

 times actually adhering to it. Brachidium a relatively short and 

 simple loop, consisting of descending lamellae, and a backward 

 arching transverse band. Devonic-Carbonic 



295. D. (Cranaena) romingeri Hall. (Fig. 376, a-c.) Devonic. 

 Small, ovate, with rounded cardinal slopes. Concentric striae 



often crowded into wrinkles near the front. 



Hamilton of New York, Michigan, 

 Indiana, Iowa. 



296. D. calvini (Hall and Whit- 

 field). Devonic. 

 Shell about I y 2 inches long by 1 % 

 inches wide and about S^ inch in 

 greatest thickness. Pedicle' valve 

 a Jt> C with umbo curved so that its fora- 

 Fig. 376. a-c, Dielasma (c'ran- men is at right angles to the plane of 

 <ena) romingeri (Pal. N. Y., IV.); separat j on f the valves. Brachial 

 d-f, D. tureidum. (After Whit- .. . , ,. c . , 



- ' , 6 valve usually with a median fold near 



field.) J 



the front. Surface smooth except 



for a few concentric growth lines. 



Chemung of Iowa, Northwest Territory. 



297. D. turgidum (Hall). (Fig. 376, d-f.) Mississippi. 



Longitudinally ovate, often very gibbous, emarginate in front. 

 Sinus present in pedicle valve and sometimes in brachial. Surface 

 marked by strong concentric growth-lines and occasionally by 

 strong wrinkles in the anterior portion. Differs from D. romingeti 

 in its greater gibbosity and in the more strongly marked sinus of 

 the pedicle valve. 



Warsaw and St. Louis of Ohio, Kentucky, Indiana, Illinois, 

 Missouri, Iowa. 



