PLATE XLIX. 
I, 10,21,22. Orbicula Nitida. (Shining Orbicula) Orate; upper valve conico-lenticular ; apex obtuse; with fine 
striae from apex to sides. 
2. Lingula Ovalis. ( Oval Lingula) Oblong-oval, smooth, depressed ; beaks rounded, blunt; base broad, circular. 
Length, 4 in.; breadth, £ in. 
3. L. Elliptica. (Elliptical Lingula.) Elongated ellipsis ; plain, with wide-set striae, radiating from umbones ; basal 
line acute. 
4. L. Squamiformis. (Scale-shaped Lingula .) Oblong, umbones acuminated; base truncated ; valves inflated above, 
compressed below; sides parallel; with longitudinal, concentric lines, and radiating striae at base. 
5. 13. Magus Pumilus. (Dwarf Magus) Beaked valve spherical, smooth, with circular edge; beak small, straight; 
flat valve depressed; hinge-line long, parallel ; with many, minute punctures. 
6. L. Mytiloides. (Mytilus-like Lingula) Oval, smooth, shining; umbones obtuse, rounded at base. 
7* L. Beanii. (Bean's Lingula) Oblong-ovate, smooth, glossy; with projecting beaks, obtuse at point ; sides parallel; 
base rounded ; with delicate lines of growth. 
8,9. 0 . Humphriesiana. (Eumphrie's Orbicula) Conical, orbicular; conical depressed; apex eccentric, obtuse; 
with many, divergent stria?. 
II, 15. L. Parallela. (Parallel Lingula) Ovate; umbones elevated ; with shallow lines of growth. Fig. 11, flatter 
valve ; fig. 15, deeper valve. 
12. L. Marginata. (Marginated Lingula) Elongated, truncated; edges of valves turned up ; sides parallel ; valves, 
with elevated, mesial ridge; with small, oval, concentric, radiating strioe. 
14. L. Obliqua. (Oblique Lingula) 
16, 26. 0 . Granulata. (Granulated Orbicula) Orbicular, conical, patelloeform ; apex acute ; sides rounded; with 
many, granulated, radiating strioe, crossed by many lines of growth. 
17, 18, 19. 0 . Reflexa. (Reflexed Orbicula) Elliptical, thin, smooth, polished; upper valve convex ; apex eccentric ; 
lower valve flat, with central vertex ; byssal sinus large. 
20. L. Scutiformis. (Scuttle-shaped Lingula) Scuttle-shaped, truncated, smooth ; with obsolete lines of growth . 
sides parallel. 
23. L. Tenuis. (Thin Lingula) 
24. Gypidium Aylesfordi. (Aylesford's Gypidium) Orbicular; with strong, longitudinal ribs; larger valve inflated ; 
beak prominent, incurved. 
25. 36, 37, 38. Spirifer Cuspidatus. (Pointed Spirifer) Inversely pyramidal, longitudinally sulcated; deeper valve 
flat on back, triangular; beak incurved; with semi-circular sinus; margin semicircular; with about fifteen sulci on each 
side of smooth undulation; with a few lines of growth and fine, longitudinal striae; foramen, with reflected edges. 
27, 28. S. Insculpta. (Carved Spirifer) Cardinal area wide, with mesial, and two or three, lateral folds, lai*ge, 
triangular, deep, acute at edges, with transverse stria?. 
29. S. Senilis. (Aged Spirifer) Cardinal area large, with transverse strioe and indistinct, mesial fold; surface 
smooth, with radiating stria?. 
30. S. Crenistria. (Creni-striated Spirifer) Cardinal area narrow ; mesial fold almost obsolete ; smooth, with many, 
divaricating stria?, crossed by strongish lines of growth. 
31. 32. G. Knightii. (Knight's Gypidium) Sub-orbicular; one small and one lai’ge valve ; beak incurved ; with 
many, longitudinal ribs, crossed by lines of growth ; cardinal area smooth, triangular. 
33, 34. S. Distans. (Distant-beaked Spirifer) Gibbose, somi-circular ; sides, with ten to twelve, longitudinal sulci ; 
cardinal area broad, triangular, curved; beaks incurved, distant; mesial ridge plain. 
35. S. SeptOSa. (Dyked Spirifer) Upper valve more convex than lower; both with wide, deep sulci, bifurcating or 
trifurcating towards margins; with two, divergent ribs on each side. 
39,40,41. G. Laevis. (Smooth Gypidium) Smooth; sub-cordiform; beaks greatly incurved; base produced. 
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