CHAPTER XXII: THE ASTARTES 



Family Astartid^ 



Shell equivalve, thick, triangular; surface ribbed; cardinal 

 teeth two or three well developed; laterals obscure; ligament ex- 

 ternal, strong; pallial line entire. 



Genus ASTARTE, J. Sby. 



Shell heavy, sub-orbicular, closed, concentrically wrinkled 

 or furrowed; epidermis thick; muscle scars two, kidney-shaped; 

 foot tongue-shaped; mantle open; gills equal, oblique, united 

 behind; siphonal orifices simple. About twenty species, bur- 

 rowers in muddy shores of northern seas. Nearly three hundred 

 fossil species. 



The Boreal Astarte (A. borealis, Chemn.) is rounded in 

 outline, barely wider than long, somewhat flattened, the umbones 

 a little nearer the anterior end. The surface is irregularly grooved 

 with rounded ridges, becoming smooth toward the margins. The 

 white surface is covered with an epidermis of yellowish brown. 

 Walruses rake these mollusks out of the mud with their tusks, 

 and swallow them whole. Length, i inch or more. 



Habitat. — New England to Arctic Ocean. 



The Chestnut Astarte (A. castanea, Say) has its dorsal 

 margin sloping up to the much elevated hinge, which, though 

 almost median in position, yet turns decidedly forward. The 

 concentric grooves are alternately strong and weak; a few faint 

 radiating lines show through the chestnut-coloured epidermis. 

 The animal's foot is bright red. Length and height, i inch. 



Habitat. — New England to New Jersey, British Isles. 



The Flat Astarte {A. compressa, Montagu) roundish, 

 flattened, with beaks elevated, and fine lines becoming obsolete 

 toward the margin, occurs from New England northward. 

 Length, f inch. 



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