122 Shell Life 



concentric ridges. The animal is yellowish white, 

 with a large foot, and tubes nearly twice the length 

 of the shell. It is a local species, found burrowing 

 in sand between low water and a depth of 12 

 fathoms. 



The Furrow-shells (Scrohicularia) are so-called on 

 account of the shape of the cartilage-pit, which is in 

 this genus a narrow chink under tlie beak. The 

 shell differs from that of Tellina in the fact that 

 while the right valve has two cardinal teeth, the left 

 has but one. The shells are white, witli concentric 

 grooving, and gape behind for the extrusion of 

 the siphons. The Prismatic Furrow - shell (S. 

 prisinatica) is almost flat, of an oblong wedge- 

 shape, thin, fragile, and semi - transparent, highly 

 polished but minutely striated. The prismatic 

 effects are due to the thinness of the epidermis. 

 The animal, which is very active, is pearly white ; 

 its foot large and pointed, its siphons slender, and 

 the mantle edges finely fringed. It is not a common 

 species, though generally distributed on sandy ground 

 in from 3 to 90 fathoms of water. It may be obtained 

 most easily from the stomachs of flat - fishes and 

 haddocks. The Glossy Furrow-shell {S. nitida) is 

 more oval than the last, and the valves gape more 

 widely. The animal is clear white, with a large 

 foot and very long siphons; the mantle is fringed 

 with short cilia. It is a more local species than 

 'pvistnatica, and occurs in muddy sand between 3 

 and 100 fathoms. 



The White Furrow-shell (Syndosmya alba) is oval, 

 thin, opaque white, polished, but with minute con- 

 centric grooves. The animal is whitish tinged with 



