2.3; 



CONCHIFERA. 



Sphenia. 



Cardita (?) oUum. Sowerby, III. p. 219, pi. 197, fig. 2. 



Gibbose, transversely obovate ; length but little less than 

 the width, and somewhat recurved ; anterior side longest, ob- 

 tuse, and plain, with from seven to ten longitudinal, nearly 

 equal, tuberculated ridges. 



Inferior Oolite, Dundry, and Cotswold Hills. 



4. Pholadomya lirata. — The Ridged Pholadoraya, pi. 

 XCV. fig. 9. 



Cardita (?) lirata. Sowerby, III. p. 220, pi. 197. fig. 3. 



Gibbose, transversely oblong, width nearly double its length ; 

 posterior side convex, provided with a large ridge, and 

 two or three tuberculated ridges ; whole surface with nine or 

 ten tuberculated ridges, and that separating the posterior side 

 tlie highest of the whole. 



Inferior Oolite, Cotswold Hills ; the Lias, at Bath and 

 Peterborough, and the Fuller's Ea-th, Alford, Wiltshire. 



5. Pholadomya deltoidka. — The Lurking Pholadomya, 

 pi. XCV. fig. 10. 



Cardita (?) deltoidea. Sowerby, II. p. 220. 



Very gibbose, obtusely triangular, with eight or nine longi- 

 tudinal, rugged, very irregularly tuberculated ridges, which 

 are longest near the posterior end ; anterior side pointed ; 

 beaks rather prominent. 



Coral Rag, Ileddington and Malton. 



6. PiioLADOiiYA DECDSSATA. — The Decussated Pholadomya, 

 pi. XCVL fig. 5. 



Cardiuin decissaliim. Sowerby, VI. p. 99, pi. .552, fig. 1. 



Coriiil'urm; posterior aide with abroad area elevated in the 

 middle, bounded by an obtuse keel ; length and breadth nearly 

 equal ; anterior side more prominent than the posterior ; 

 beaks incurved ; surface with strong longitudinal ribs, and 

 decussated by irregular transverse ones, becoming closer as 

 they approach the base of the valves. 



Chalk Marl, Hamsey, Sussex, and Speeton. 



7. Pholadomya ambioua. — The Ambiguous Pholadomya, 

 pi. XCV. fig. 4. 



Lutraria amhigiia. Sowerby, III. p. 48, pi. 227. 



Transversely elongated, gibbose, a little recurved, gaping 

 anteriorly ; surface with several oblique divergent furrows. 



This species is variable in width, some specimens being neaily ob- 

 ovate and teeth stronger, and, in general, Icnotted ribs. 



The Inferior Oolite, Cotswold Hills, and the Lias, Weston, 

 Yorkshire. 



8. Pholadomya fidictjla. — The Harp Pholadomya, pi. 

 XCVI. fig. 2. 



Lutraria lirata. Sowerby, III. p. 47, pi. 225. 



Trautiversely elongated, its width twice and a half its 

 length ; gibbose, recurved ; surface with numerous obliquely 

 longitudinal ridges; the anterior side almost smooth, and 

 somewhat compressed. 



The Inferior Oolite, Cotswold, and the Blue Wick. 



9. Pholadomya ovalis. — The OvalPholadomya.pl.XCVI. 

 fig. 4. 



Lutraria okuHs. Sowerby, III. p. 47, pi. 226. 



Transversely elongated, elliptical and mostly straight, some- 

 what convex ; curvature of front and back nearly equal ; sides 

 rounded and slightly gaping, the posterior one considerably 

 the smallest, with only one furrow on it ; surface with about 

 nine divergent longitudinal ridges. 



The Portland Stone, Felmersham, Portland, and the Corn- 

 brash, Scarborough. 



10. Pholadomya angustata. — The Narrow Pholadomya, 

 pi. XCVI. fig. 8. 



Lutraria angustata. Sowerby, IV. p. 29, pi. 327. 



Transversely elongated, gibbose, anterior side rather com- 

 pressed ; posterior side rounded, and extends a little way from 

 the beaks ; surface with about twelve oblique acute ribs, which, 

 as well as tlie intervening furrows, are decussated by numerous 

 irregular transverse strice ; substance of the shell thin, and in 

 consequence the ribs are nearly as conspicuous internally as 

 without. 



The Inferior OoliJe, Dundry. 



11. PnoL.vDOMYA McRCULsoNi. — Murchison's Pholadomya, 

 pi. XCVI. Hg. C. 



P. Murchisoni. Sowerby, VI. p. 87, pi. 545, fig. 1. 



Oval, beaks large ; posterior side short, provided with six or 

 seven elevated, obtusely round, divergent, longitudinal ribs, 

 intersected by strong, undulating, wide-set furrows, giving the 

 ribs a knotted appearance. 



From the Roof of the Coal Workings, Brora. 



12. Pholadomya nana. — The Dwarf Pholadomya, pi. 

 XCV. fig. 2. 



P. nana. Phillips, Geo. York, I. pi. 9, fig. 7. 



Transversely elongated ; posterior side nearly straight ; 

 beaks large and obtuse ; anterior side rounded ; surface with 

 concentric lines of growth, and a few nearly obsolete radiating 

 furrows towards the base, in the middle of the valves ; basal 

 line nearly straight. 



The Great Oolite, White Nab, Yorkshire. 



13. Pholadomya obsoleta. — The Obsolete Pholadoraya, 

 pi. XCV. fig. 3. 



P. obsoleta. Phillips, Geo. York, 1 pi. 5, fig. 24. 



Transversely elongated ; beaks obtuse, situate towards the 

 posterior side, which is short and a little narrowed ; anterior 

 side somewhat wider and rounded ; surface with concentric 

 furrows, and four radiating narrow furrows from the beaks to 

 the basal line. 



The Great Oolite, Brandsby. 



14. Pholadomya Phillipsii. — Phillip's Pholadomya, pi. 

 XCV. fig. 11. 



P. Murchesoni. Phillips, Geo. York, I. p. 27, fig. 9. 



Transversely oval, much inflated ; beaks produced, conside- 

 rably incurved, situate nearest the posterior sides, which is 

 shortest, and with long, longitudinal, narrow ribs, which 

 radiate from the b'eaks to the basal margin, projecting a little 

 beyond it, giving a scolloped aspect, and occupying about half 

 the valve ; anterior to these, two radiating narrow furrows ; 

 the anterior side rounded, and slightly contracted below. 



The Cornbrash, Scarborough. 



15. Pholadomya compbessa. — The Compressed Phola- 

 domya, pi. XCV. fig. 5. 



Transversely elongated, somewhat heart-shaped, oblique, 

 compressed ; beaks large, prominent, and quite approximating; 

 surface with six large distant radiating ribs, leaving a large 

 bare space between them and the beaks. 



The Great Oolite, Kettering, Northamptonshire. 



16. Pholadomya cuneata. — The Wedge-Shaped Phola- 

 domya, pi. XCV. fig. 7. 



