415 Modi. 



stToia (see T3, 109). In Bedford Co. it was found by Steven- 

 son in sandstone bed No. 30 the Yellow Creek section, Hopewell 

 township, 2957 feet below the assumed base of Catskill forma- 

 tion. — VIII G, g. — See spec. 801-27 from Marshall's creek, 

 Monroe Co., Pa. (00, p. 235); spec. 809-6, from canal at Port 

 Jervis, in Hamilton strata^ VIII c. 



Modiomorpha neglecta ? See Claypole's Barnett's MilL 

 Perry Co., specimen 5-98, reported in Cat. 000, as from 

 Hamilton upper shales. VIII c. 



Modiomorpha quadrula ? Hall Prelim. Not. Lam. 1870, 

 Chemung. — See Claypole's spec. 104-28, from opposite Sher- 

 mansdale mill. Perry Co., in King^s Mill sandstone^ Chemung- 

 CatsMll transition heds, VIII g — IX, — See specimen 876-4 

 (00, p. 237) in L. E. Hick's collection near Big Shanty, Mc- 

 Kean Co., Pa. Chemung VIII g. — See Appendix. 



Modiomorpha rigidula, Simpson, n. sp.. Trans. Amer. 



Philos. Soc, Phila., 1889, page 449, fig. 16. 

 Shell of medium size or smaller, subquad- 

 rangular in outline ; height a little more than 

 three-fifths the length of the shell; basil 

 APS. iTr.ifisr margin regularly and gently curving from the 



anterior to the post-basil extremity ; posterior margin gently 

 curved, slightly oblique, sometimes nearly at right angles to the 

 basil margin ; cardinal line essentially straight ; anterior rounded 

 abruptly, extended, without limitation by a sinus. Beaks a little 

 more than one-fourth the length of the shell from the anterior 

 end ; umbonal ridge prominent, extending from the beaks to the 

 postbasal extremity. Valves convex towards the basal mar- 

 gin, becoming gibbous above the middle and in the umbonal 

 region ; posterior slope convex near the beaks, becoming flat- 

 tened as it approaches the posterior margin. Surface marked 

 by concentric striae which frequently become obsolete on por- 

 tions of the shell. On casts of this species the pallial line is 

 sometimes so strong as to give a distorted appearance to the 

 specimen. This species may be distinguished from Modio- 

 morpha rigida^ of this formation, by its greater gibbosity, the 

 less oblique posterior margin, less clearly defined umbonal 

 ridge, and the more prominent beaks. Formation and locality, 

 Chemung group,, Tioga village, Tioga Co. Pa. — VIII g. 



