424 MOLLUSCA. CARDIADiE. Pholadomy^a. 



8. C. semigranulatum Gibbose, transverse, subtriangular, longitudinally 



striated, posterior side straight, longitudinally sulcated, and largely granu- 

 lated. — Sower. Min. Conch, t. cxliv. — London Clay. 



y. C. migustatum Transversely elongated, thin, rather depressed ; costae 



twenty-seven, margin toothed ; retrally truncated, anteally rounded— Sowej*. 

 Min. Conch, t. cclxxxiii. f. 2 — Crag. 



1 0. C. edulinum. — Nearly orbicular, convex, slightly oblique, thick ; costae 

 eighteen, rugose ; slightly truncated retrally. — Soiver. Min. Conch, t. cclxxxiiL 

 f 3 — Crag. 



1 1. C. turgidum Obovate, transverse, smooth, gibbose ; longitudinally 



striated retrally ; edge minutely toothed. — {Brander, 96.) — Sower. Min. 

 Conch, t. cccxlvi. f. 1. — London Clay. 



12. C. poridosum. — Orbicular, retrally obscurely truncated, longitudinally 

 sulcated, with a row of erect, approximate spines united near their points, 

 alternating with each sulcus; sulci terminated by ligulate teeth. Var. 

 spines united through their wliole length by a membrane, and their bases 

 sunk beneath the edges of the sulci — {Brander, 99.) — Sower. Min. Conch, 

 t. cccxlvi. f. 2 — London Clay. 



13. C striatulum. — Orbicular, convex, concentrically striated, posterior side 



longitudinally striated, with a toothed edge Sower. Min. Conch, t. Dliii. f. 1. 



— In Lias. 



14. C. truncatum — Transversely ovate, gibbose, smooth; posterior side 

 obliquely truncated, longitudinally sulcated ; beaks small — (C. peciinatum. 

 Young, and Brit. Geol. York. 226. t. viii. f. 5.) — Sower. Mm. Conch, t. cliii. 

 f, 3. — In Lias. 



15. C. dissimile — Transversely obovate, gibbose, smooth ; posterior side 

 bounded by a small rib, longitudinally striated ; front rather sti'aight. — Sower. 

 Min. Conch, t. Dliii. f. 2.— Upper Oolite. 



16. C. decussatum — Cordiform antiquated, longitudinally ribbed, anterior 

 margin rounded ; posterior side a broad area raised in the middle ; length 

 ,4ind breadth nearly eqnal.^-iV/an«. Geol. 126. t. xxv. f. 3. 



Gen. FHOLADOMYiEA.— " A transverse, tliin, subhya^ 

 line, ventricose shell ; the posterior portion short, rounded ; 

 the anterior more or less elongated and gaping ; hinge 

 composed of an elongated subtrigonal faveola, and a mar- 

 ginal plate in each valve, with a rather short external liga- 

 ment ; the muscular impressions two, indistinct ; the sinus 

 in the impression of the mantel large ; tlie umbones ap- 

 proximated ."" — Sowerby. 



1. P. pvoducta — Transversely oblong, gibbose, with six or seven angular 

 •longitudinal ridges ; produced side plain.— i^ozwr. Min. Conch, t. cxcvii. f. 1. 

 — Inferior Oolite. 



2. P. obtusa — Ti'ansverscly oljovato, recurved, gibbose, with from seven to 



:le\\ longitudinal, nearly equal, tuberculated ridges Sower. 'Mm. Conch. 



:t. cxc>'ji. f. 2 — Jr/crwr 'OoW.e. 



