BRACHIOPODA — TELOTREMATA. 313 



B. Cardinal area of pedicle valve not strongly arched **. 



** Beak incurved and pronounced 319. C. hamiltonensis. 



** Beak inconspicuous. Cardinal area of pedicle valve almost vertical I. 



I. 2 to 5 plications on each side of fold and sinus 322. C. acutirostris. 



I. 6 to 9 plications on each side of fold and sinus 318. C. dalmani. 



318. C. dalmani (Hall). Devonic. 

 Brachial valve semicircular ; mesial fold flat ; beak scarcely de- 

 fined. Concentric lamellae strong. Surface granulose-punctate. 



Helderbergian of New York, Tennessee, Missouri and New 

 Brunswick. 



319. C. hamiltonensis Hall. (Fig. 393, a-c.) Devonic. 

 Beak slightly incurved and frequently distorted. Surface marked 



with 6-8 plications on each side of the well marked sinus and fold. 



Fig. 393, a-c. Cyrtina hamiltonensis ; d-e, Cyrtina alpenensis 

 (Pal. N. Y. IV. and VIII.) 



Onondaga, Hamilton and Portage ; distributed throughout North 

 America. 



320. C. umbonata (Hall). Devonic. 

 Differs from C. Iiamiltonensis in its broader, arcuate and incurved 



umbo and beak and in that the 5 or 6 plications on each side of 

 the mesial fold and sinus become obsolete before reaching the 

 umbo, thus leaving that smooth or nearly so. 

 Hamilton of Illinois, Missouri, Iowa, Michigan. 



321. C. alpenaensis Hall and Clarke. (Fig. 393, d-e.) Devonic. 

 Very similar to C. umbonata but is larger, with broad well de- 

 fined plications and smooth median fold and sinus. 



Hamilton of Michigan. 



322. C. acutirostris (Shumard). Mississippic. 

 Small. Pedicle valve with very high and nearly vertical cardinal 



area. Brachial valve depressed-convex. Surface with two to five 

 simple rounded plications on each side of the median fold and 

 sinus; these are crossed by imbricating growth lines. Differs 



