MOLLUSCA. ARCADiE. 
CU0UL-«A. 
399 
beaks ; edge toothed within — Sower. Min. Conch, t. cclxxvi. f. 3. — London 
Clay. 
5. A. quadrisulcata .-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. 
G. A. pulclira . — Transversely ovate-elongated, depressed, finely striated; 
anterior side rather impressed, obliquely truncated ; beaks close.— -(Sower. Min. 
Conch, t. cccclxxiii- f. 3 — In Oolite. 
7. A. duplicata . — Transversely ovate-elongated, convex, longittidinally rib- 
bed ; ribs suleated along the middle ; margin toothed ; beaks close. — Sower. 
Min. Conch, t. cccclxxiv. f. 1.— In London Clay. 
8. A. depressa — Elongated transversely, depressed, marked with elevated 
and crenulated striie ; extremities rounded ; marginal sinus obscure — Sower. 
Min. Conch, t. cccclxxiv. f. 2.— In Plastio Clay. 
9. A. tumida — Transversely elongated, gibbosa, costated? Anterior side 
pointed ; marginal sinus short, deep ; beaks distant. — Soioer. Min. Conch, t. 
cccclxxiv. f. 3. — In Magnesian Limestone* 
10. A. cancellata.^Tvf\Qe as wide as long, convex, longitudinally and 
transversely suleated ; anterior side defined by a keel, truncated ; posterior 
side rounded ; marginal sinus short, but deep ; beaks nearly close Mart, 
l)erb. t. xliv. f. L— 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 
striie ; 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 Carboniferous Limestone. 
Gen. CUCULiEA. — Shell subtransverse, ventricose ; hinge 
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 Parle. Org. Rem. iiL 
171. Sower. Min. Conch, t. Ixvii — 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. cevi. f. 3, 4. — Green Sand. 
3. C. Transversely oblong, gibbose, longitudinally striated ; an- 
terior side wedge-shaped ; lines beneath the cartilage numerous.— (Vower. 
Min. Conch, t. cevi. f. 1 , 2. — Inferior Oolite. 
4. C. carmafe.— Obliquely cuneiform, smooth ; anterior side pointed, and 
distinguished by a ridge running up the heok.— Sower. Min. Conch, t. cevii. 
f. 1. — In Green Sand. 
5. C. fibrosa — Obovate, gibbose, with numerous longitudinal elevated striie 
