BRACHIOPODA — TELOTREMA TA. 319 



by 3 to 4 strong, subangular plications on each side of the fold and 

 sinus. Mesial sinus broad and deep. Entire surface covered with 

 fine radiating striae. 



Niagaran of Kentucky, Indiana, Wisconsin. 



328. S. niagarensis (Conrad). (Fig. 400.) Siluric. 

 Of moderate size, convex with nearly equal valves. Pedicle 



valve with strongly incurved beak. Surface covered with many 

 fine depressed plications which become ob- 

 solete toward the extremities and sometimes 

 appear quite flattened out. Fine, thread-like j 

 radiating striae cover plications and inter- 

 spaces alike. '1 

 Niagaran of New York, Indiana., ^^pBI 



329. S. (Delthyris) sulcatus Hisinger. FlG - 4 °°- y s £ ri {' r 



D f_. v ,., . niagarensis (Pal. N. Y., 



(rig. 401.) Siluric. TT y 



Gibbous. Valves unequal. Hinge line 

 more or less extended, often mucronate. Plications 4 to 7 on each 

 side of the mesial fold and sinus, crossed by strong imbricating 

 lamellae and longitudinally marked by fine striae. 



Niagaran of New York, Ontario. 



v/ , ; v ' . 





% 



FlG. 401. Spirifer {Delthyris) sulca- FlG. 402. Spirifer crispus ( Pal. N. 



tus, with striae enlarged (Pal. N. Y., II.). Y., II.). 



330. S. crispus (Hisinger). (Fig. 402.) Siluric. 



Small. Pedicle valve very convex with incurved beak and high 

 cardinal area. Surface marked by broad plications, from 6 to 8 on 

 each valve, strongest near fold/and sinus and crossed by fine, 

 thread-like concentric striae. 



Niagaran of New York, Indiana, Ontario, Nova Scotia. 



