PLATE LXVIII. 
1. Catillus Sulcatus. ( Farrowed Catillus.) Oblong, inequivalve; beaks prominent, that of 
one valve incurved, acute; surface, with about nine, large, longitudinal plaits. 
2. C. Dubius. ( Doubtful Catillus.) Concave, ovate, pointed; valves unequal; beaks short, 
pointed ; surface, with concentric stria) and indistinct undulations. 
3. C. Striatus. ( Striated Catillus.) Sub-globose, plain; anterior side concave, smooth ; beaks 
short, obtuse; surface, with shallow, concentric sulci and stria). 
4. Hinge of Catillus Brongniartii. V. Figs. 5, 6. 
5. 6. C. Brongniartii. ( Brongniart’s Catillus.) Oblong, gibbose; posterior side cordiform, 
angular, lobed; anterior side truncated, flat, smooth; beaks small, curved, acute; surface, with large, 
transverse undulations. 
7. C. PictUS. ( Painted Catillus.) Convex, oblong; valves equal; anterior side flattened, 
smooth; surface wavy, almost covered with small, concentric sulci, and generally with longitudinal 
stripes of brown colour. 
8. C. LatUS. ( Broad Catillus.) Depressed, ovate-rliomboidal ; valves equal; anterior side 
concave; posterior side broad, expanding; hinge-line oblique; beaks small, short; surface, with 
concentric undulations and sharp stride. 
9. Avicula Tenua. ( Thin Avicula.) Oblique, compressed; hinge-line oblique ; anterior side 
straight, with auricle undefined; posterior side, with curvature under ear; surface smooth, with 
irregular, concentric wrinkles. 
10. A. Squamula. ( Scale Avicula.) Oblique, compressed; hinge-line oblique; anterior side 
straight; posterior side curved ; surface smooth, with a few, concentric wrinkles. 
11. C. Concentricus. ( Concentric Catillus.) Ovate, inequivalve ; beaks produced, incurved, 
transversely undulated and striated; liinge-line, with about twelve grooves for reception of ligament. 
12. C. InvolutuS. ( Involute Catillus.) Globular; valves unequal; one valve inflated, with 
large, incurved beak, the other flat, with deep, concentric undulations; margin thick, deflected. 
13. Hinge of Catillus Involutus. V. Fig. 12. 
14. C. Digitatus. ( Fingered Catillus.) Very large, with large, longitudinal sulci, with inter¬ 
vening ribs round, and crossed by distinct lines of growth. 
15. C. Cordiformis. ( Heart-shaped Catillus.) Equivalved, cordiform ; anterior side angular ; 
posterior side undefined; beaks large, incurved; surface transversely waved. 
16. C. Gryphseoides. {Gryphce-formed Catillus.) Ventricose, ovate ; inequivalve, the smaller 
globose; beaks incurved, acute ; surface concentrically undulating. 
17. C. Kellyii. {Kelly’s Catillus.) Mytiliform, elongated, smooth; with concentric lines of 
growth; umbones small, rounded; valves narrow above, rounded and wide towards base. 
18. C. Minutus. {Minute Catillus.) Modioliform, smooth; with distinct lines of growth; 
umbones small, rounded. Length, f 2 in.; breadth somewhat less. 
19. A. Humata. {Buried Avicula.) V. Plate LXVI.**, Fig. 1. 
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