BRACHIOPODA — TELOTREMATA. 317 



g. Hinge line extended io / . 



ic/. Cardinal area high c f . 



c f . Plications few (2-5) on each side the mesial fold 



and sinus 22. 



22. Plications broad, nearly equalling the mesial 



sinus in width 343. S. raricosta. 



22. Plications much narrower than mesial sinus. 

 335. ,5. perlamellosus. 



c f . Plications many 338. S. murchisoni. 



ic/. Cardinal area linear d' '. 



d' '. Plications few (7 or 8 on each side the mesial fold 



and sinus) 340. S. ditodenarins. 



d / . Plications many 354. S. miicronatus. 



ff Plications marked by radiating stride t'ttt- 



XXXX Cardinal area wide 5. 



5. Plications few (3-4 on each side the mesial fold and sinus). 



327. S. eudora. 



5. Plications many //. 



h. Shell small {% inch wide) 358. S. tullius. 



h. Shell of medium size or large ii / . 



ii / . Hinge line much extended. Shell often inequilateral. 



351 . S. iowaensis. 

 \\> '. Hinge line only slightly longer than width of shell 



below e' . 



e' '. Cardinal area subsemicircular.. 347. S. euryteines. 



e' . Cardinal area subtriangular 348. S. furnacula. 



XWX Cardinal area narrow 6. 



6. Plications few (2 or 3 on each side mesial fold and sinus). 



334. S. macropletira. 



6. Plications many i. 



i. Fold and sinus rapidly expanding. Shell large. 



359. S. mesistrialis. 



i. Fold and sinus slowly expanding 328. S. niagarensis. 



Plications granulose, sometimes in radiating lines 5J. 



5J Groove usually present in fold. Shell large 7. 



7. Granules scattered, sinus deep, angular 350. S. granulosus. 



7. Granules in lines, sinus rounded 349. S.oweni. 



5+ No groove in fold. Shell of medium size 355. S. asper. 



ft Plications apparently smooth 6 J. 



6X Shell very convex 8. 



8. Large (over 2 inches wide) /. 



j. Hinge line shorter than width of shell below. 



367. 6". neglect us. 



j. Hinge line forming greatest width of shell I2 / . 



I2 / '. Shell very ventricose with prominent triangular fold. 



345. 5. acuminatus. 

 I2 / '. Shell moderately gibbous with low, rounded fold. / / . 



f. Plications numerous (30-35) 349. S. cweni. 



/'. Plications few ( 10-16) 338. S. murchisoni. 



8. Small (about ^ inch wide), often with conspicuous concentric 

 lines developed toward the front k. 



