381 



MANUAL OF THE MOLLtTSCA. 



adductor scar central, near tlio umbo ; cardinal impressions 

 lateral, striated. 



Fig. 189. Productus giganteus, \ Carb. limestone. 

 A, interior of dorsal valve; B, interior of ventral valve, with the timbo removed; 

 C, ideal section of both valves ; D, hinge-line of A ; j, cardinal process ; a, adductor • 

 r, cardinal muscles; b, oral processes?; s, hollows occupied by the spiral anus; v, 

 vascxilar impressions ; h, hinge-area. 



Pkoductus, Sowerby. 



Types, P. giganteus, Martin. z=Anomia produda, Martin. 



Examples, P. liorridus, PL XY., Fig. 27. P. proboscideus, 

 PI. XY., Fig. 28. 



Shell free, auriculate, beak large and rounded ; spines scat- 

 tered ; liinge-area in each valve linear, indistinct ; no hinge- 

 teeth ; cardinal process lobed, striated ; vascular impressions 

 simiDle, curved ; ventral valve deej), with two rounded or sub- 

 spiral cavities in fr'ont. These shells may have been attached 

 by a pedicle when ^^oung, the impressions of the pedicle-muscle 

 blending with those of the hinge-muscles (c) in the ventral 

 valve. A few species appear to have been jDermanently 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 have 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 



