Cucul.ea. MOLLUSCA. ARCADE. 399 



beaks; edge toot lied within — Sower. Min. Conch, t. cclxxvi. f. 3 — London 

 Clay. 



5. A. quadrisidcala Twice as wide as long, convex, longitudinally striated ; 



anterior side truncated, defined by a keel, and marked by four deep furrows; 

 posterior side small, rounded ; marginal sinus large — Sower. Min. Conch, t. 

 cccclxxiii. f. 1. — In Oolite. 



6. A. pidckra.— Transversely ovate-elongated, depressed, finely striated ; 

 anterior side rather impressed, obliquely truncated ; beaks close — Sower. Min. 

 Conch, t. cccclxxiii. £ 3 — In Oolite. 



7. A. duplicata Transversely ovate-elongated, convex, longitudinally rib- 

 bed ; ribs sulfated along the middle ; margin toothed ; beaks close. — Soiver. 

 Min. Conch, t. cccclxxiv. f. 1. — In London Clay. 



8. A. depi-essa Elongated transversely, depressed, marked with elevated 



and crenulated stria? ; extremities rounded ; marginal sinus obscure — Sower. 

 Min. Conch, t. cccclxxiv. f. 2. — In Plastic Clay. 



9. A. tumida. — Transversely elongated, gibbose, costated? Anterior side 

 pointed ; marginal sinus short, deep ; beaks distant. — Soiver. Min. Conch, t. 

 cccclxxiv. £ 3 In Maynesian Limestone. 



10. A. cancellata — Twice as wide as long, convex, longitudinally and 

 transversely sulcated ; anterior side defined by a keel, truncated ; posterior 



side rounded ; marginal sinus short, but deep ; beaks nearly close Mart. 



Derb. t. xliv. f. 7-— Sower. Min. Conch, t. cccclxxiii. f. 2 — Carboniferous Lime- 

 stone. 



11. A. rostrata. — " Valves equal, scaleniform ; one end of the shell length- 

 ened into a straight, smooth, conical rostrum ; the other end short, gibbous, 

 and marked from the beaks to the margin with very neat equal and acute 

 stria? ; the margin in this part of the shell crenulated ; the beaks are small, 

 pointed, and approximate, placed over the shorter extremity.".— Mart. Derb. 

 t. xliv. f. 6. — In Carbo?iiferous Limestme. 



Gen. CUCULiEA. — Shell subtransverse, ventricose ; hino-e 

 with numerous small teeth, with from two to five parallel 

 plates ; ligament subexternal ; anterior muscular impres- 

 sion with an elevated margin. 



1. C. glabra. — Rhomboidal, anterior angle obtuse, posterior edge of the 

 front rounded ; surface covered by fine longitudinal lines, decussated by the 

 lines of growth ; teeth of the hinge deeply striated. — Park. Org. Rem. iii. 

 171. Sower. Min. Conch, t. lxvii. — Green Sand. 



2. C. decussata. — Transversely ovate ; gibbose, with flattish longitudinal 

 ridges ; anterior side angular ; lines beneath the cartilage few — Park. Org. 

 Rem. iii. 171- Sower. Min. Conch, t. ccvi. £ 3, 4 — Green Sand. 



3. C. oblonga. — Transversely oblong, gibbose, longitudinally striated ; an- 

 terior side wedge-shaped ; lines beneath the cartilage numerous — Soiver. 

 Min. Conch, t. ccvi. f. 1 , 2. — Inferior Oolite. 



4. C. carinala. — Obliquely cuneiform, smooth ; anterior side pointed, and 

 distinguished by a ridge running up the beak.— Sower. Min. Conch, t. ccvii. 

 £ 1. — In Green Sand. 



5. C. fibrosa — Obovate, gibbose, with numerous longitudinal elevated striae 



