BRACHIOPODA — TELOTREMATA. 



Fig. 406. Spirijer macropleura (Pai. \. Y., VIII.). 



produced anteriorly into a linguiform extension. Brachial valve 

 convex in the middle with closely incurved beak. Surface marked 

 by 4 to 6 strong plications on each side the median line and con- 

 centrically crossed by regular imbricating larnelke which are 

 strongly arched in passing over the 

 plications, giving the surface a rough 

 appearance. 



Helderbergian of Maine, New York, 

 Pennsylvania, Maryland, Tennessee, 

 Missouri. 



,r\y >v-. 



336. S. cyclopterus Hall. Devonic. 

 Semicircular. Hinge line usually 



shorter than width of shell below. Con- 

 vexity of valves nearly equal. Surface 

 marked by 7 or more rounded plica- 

 tions on each side of the mesial fold 

 and sinus, concentrically crossed by 

 fine, close, lamellose striae. 



Helderbergian and Oriskanian of 

 Appalachian region (Maryland to New 

 Brunswick and Gaspe). 



337. S. concinnus Hall. (Fig. 408.) 

 Semicircular. Hinge line usually shorter than the width of the 



shell below. Beak of pedicle valve elevated and incurved. Sinus 

 and fold angular and sometimes marked by obscure plications 

 toward the front. Plications rounded, 12-14 on ea ch side of the 

 median line and crossed by concentric striae. Differs from 5. 



Fig. 407. Spirifer (Delihy- 

 ris) perlamellosus (Pal. N. Y., 

 VIII.). D, deltarium ; F, for- 

 amen ; S, median septum ; /, 

 teeth. 



Devonic. 



