RYon MANUAL OF THE MOLLUSCA. 
adductor scar central, near the umbo; cardinal impressions 
lateral, striated. : 
aN vin) y 
Fig. 189. Productus giganteus, + Carb. limestone. 
| A, interior of dorsal valve; B, interior of ventral valve, with the wmbo removed: 
C, ideal section of both valves; D, hinge-line of A; 7, cardinal process; a, adductor3 
7, cardinal muscles; 0, oral processes?; s, hollows occupied by the spiral arms; v, 
\ vascular impressions ; 4, hinge-area. 
PRODUCTUS, Sowerby. 
Types, P. giganteus, Martin. —Anomia producta, Martin. 
Examples, P. horridus, Pl. XV., Fig. 27. BP. proboscideus, 
PLO, ie. 28. 
Shell free, auriculate, beak large and rounded; spines scat- 
tered; hinge-area in each yalve lnear, indistinct; no hinge- 
teeth ; cardinal process lobed, striated; vascular impressions 
simple, curved; ventral valve deep, with two rounded or sub- 
spiral cavities in front. These shells may haye been attached 
by a pedicle when young, the impressions of the pedicle-muscle 
blending with those of the hinge-muscles (c) in the ventral 
yalye. A few species appear to have been permanently fixed. 
P. striatus is irregular in its growth, elongated and tapering 
towards the beak, and occurs in numbers packed closely together. 
P. proboscideus seems to haye lived habitually in cavities, or 
half-buried in mud,.as suggested by M. D’Orbigny; its ventral 
valve is prolonged several inches beyond the other, and has its 
