Metoptoma. 



MOLLUSCA. 



105 



Obovate, its length and breadth being nearly equal, depres- 

 sed ; vertex eccentric, situate about one-third of the length of 

 the shell from the anterior end ; external surface with about 

 thirty obtuse, distant, rounded, divergent ribs, those upon the 

 posterior end strongest. 



Lower Oolite, Stonefield. 



8. Patella Nanus — The Dwarf Patella, pi. XL VIII. fig. 

 24, 25, 26. 



Patella Nanus. Sowerby, V. p. 134, pi. 484, fig. 3. Fle- 

 ming, p. 288. 



Oblique, smooth, subconic ; vertex obtuse, situate half way 

 between the centre and the anterior end of the shell ; both 

 extremities equally obtuse ; aperture oval. Fig. 26, the natural 

 size of the shell. 



The London Clay, Ancliffe. 



9. Patella ancyloides.— The Ancilla-shaped Patella, pi. 

 XL VIII. fig. 27, 28, 29. 



Patella ancyloides. Sowerby, V. p. 134, pi. 484, fig. 2. 



Convex, smooth, depressed ; vertex slightly spiral, situate 

 near the anterior end ; the apex curved downwards, and a little 

 to one side. Fig. 29, natural size of the shell. 



The London Clay at Ancliflfe. 



10. Patella retrosa. — The Retroflexed Patella, pi. 

 XLVIII. fig. 30. 



Patella retrosa. Phillips, II. p. 223, pi. 14, fig. 5. 



Subconic, smooth, depressed ; apex retroflexed, acute, placed 

 about two-thirds towards the anterior end; with about fourteen 

 broad, flat, divergent, undulating ribs, and shallow, broad, inter- 

 mediate furrows ; aperture elliptical ; margin undulated. 



Mountain Limestone, BoUand. 



11. Patella jequalis. — The Equal Patella, pi. XLVIII. 

 fig. 31, 32. 



Patella cequalis. Sowerby, II. p. 87,* pi. 139j fig. 2. Fle- 

 ming, p. 288. 



Abruptly conical, its height and breadth being nearly equal, 

 smooth, with a few obsolete radii ; posterior end nearly perpen- 

 dicular; apex obtuse; base oviform, the anterior end broadest. 



In the Crag at Holywells. 



12. Patella curvata. — The Curved Patella, pi. XLVIII. 

 fig. 33. 



Patella curvata. Phillips, II. p. 223, pi. 14, fig. 4. 



Conical, smooth ; anterior end curved ; vertex inclined pos- 

 teriorly, acute at the apex ; aperture deep and orbicular ; mar- 

 ginal lip plane. 



The Mountain Limestone, BoUand. 



13. Patella latissima The Very Broad Patella, pi. 



XLVIIL fig. 35. 



Patella latissima. Sowerby, II. p. 85, pi. 139, fig- I and 5. 

 Fleming, p. 288. 



Depressed, smooth, and very thin; vertex eccentric, flat; 

 concentrically undulated; aperture nearly orbicular, or slightly 

 oval. 



In the Slaty Clay, Lincolnshire. 



14. Patella lateralis. — The Lateral Patella, pi. 

 XLVin. fig. 36. 



Patella lateralis. Phillips, II. p. 223, pi. 14, fig. 6. 



Subconic, smooth ; vertex depressed ; the apex acute ; pro- 

 vided with a lateral sulcus, and posterior radiations. 



The Mountain Limestone, BoUand. 



Genus X.— METOPTOMA.— PA«7/?>*. 

 Shell subcorneal, depressed; vertex subcentral; face 

 under the apex truncated; general form somevrhat shield- 

 shaped. 



1 . Metoptoma imbricata. — The Imbricated Metoptoma, 

 pi. XLVIII. fig. 35 and 40. 



Metoptoma imbricata. PhiUips, II. p. 224, pi. 14, fig. 8. 



Conical, shield-shaped ; apex rather obtuse ; surface covered 

 with concentric, imbricated ribs. 



The Mountain Limestone at BoUand, and near Dowall, Der- 

 byshire. 



2. Metoptona sulcata. — The Furrowed Metoptoma, pi. 

 XLVIIL fig. 37. 



Metoptoma sulcata. PhiUips, II. p. 224, pi. 14, fig. 11. 

 Convex; posterior side arcuated; outer surface concentricaUv 

 sulcated ; apex obtuse. 



Mountain Limestone, BoUand. 



3. Metoptoma oblonga — The Oblong Metoptoma, pi. 

 XLVIII. fig. 38. 



Metoptoma oblonga. PhiUips, II. p. 224, pi. 14, fig. 10. 

 Oblong, cordiform ; conical, rather convex ; expanded ante- 

 riorly, with the margin rounded ; vertex obtuse. 

 Mountain Limestone, BoUand. 



4. Metoptoma pileus The Bonnet Metoptoma, pi. 



XLVIII. fig. 39. 



Metoptoma pileus. Phillips, II. p. 224, pi. 14, fig. 7- Brown. 

 Elts. Foss. Conch, p. 67, pi. 5, fig. 1 8. 



Shield-shaped, conical, smooth ; apex obtuse. 

 Mountain Limestone, BoUand, and Dowall, Derbyshire. 



5. Metoptoma elliptic a The Elliptical Metoptoma, 



pi. XLVIIL fig. 41. 



Metoptoma elliptica. PhiUips, II. p. 224, pi. 14, fig. 9- 

 EUiptical, subconic, smooth ; vertex terminal, acute, and 

 elongated. 



Mountain Limestone, BoUand. 



2d 



