EAST COAST MARINE SHELLS 



39 



are wrinkles and corrugations. Length 



30 mm. 



PI, 12, Fig. 2 



North Carolina to Gulf of Mexico; 



West Indies 



SECTION MYOFORCEPS Fischer 1886 



LITHOPHAGA ARISTATA Dlllwyn (L. caudlgera 

 Lam. and L. forflcata Rav.). Erect Date. 

 A white, thin, fragile shell; posterior 

 end with a third valve, a narrow projec- 

 tion; color light salmon inside. Length 



31 mm. 



It has been taken alive in pieces 

 of coral at Charleston bar. South Carolina. 

 PI. 8, Fig. 8 



North Carolina to West Indies; 

 Mexico 



GENUS MODIOLARIA Beck 1838; 

 Musculus Roeding 1798, not Martyn 1787 



Shell inflated, often with three 

 areas on disk; surface ribbed or smooth; 

 umbones incurved, placed near anterior end. 



MODIOLARIA CORRUGATA Stimpson. Shell oval, 

 heart-shaped when viewed in front, upper 

 margin compressed and arching; sixteen or 

 more ribs on anterior compartment, those 

 in posterior compartment more crowded and 

 distant; minute wrinkles of epidermis 

 crossing ribs and middle section visible 

 under a microscope; epidermis yellowish 

 green; interior silvery, edge toothed by 

 the ribs. Range 2-100 fathoms. Length 

 12 mm. 



PI. 12, Fig. 9 



PI. 72, Fig. 9 



Greenland to North Carolina; Cir- 



cumpolar 



MODIOLARIA NIGRA Gray. Shell thin; um- 

 bones prominent, scarcely touching each 

 other, placed far from anterior end; sur- 

 face with network of minute growth lines; 

 many fine radiating lines or ridges; epi- 

 dermis rusty brown; interior livid with 

 silvery lustre and fine radiating lines. 

 Length .75-1 Inch. Depth range 1-60 fath- 

 oms. 



PI. 13, Fig. 11 



Greenland to North Carolina 



MODIOLARIA LATERALIS Say. Ends sculptured 



with fine beaded ribs; fine concentric 

 growth lines throughout; inner margin 

 toothed except in middle and ligament area. 

 Length 6 mm. to over an inch. 



The shell is remarkable for its 

 rich chestnut color, becoming almost black 

 toward the umbones. It spins a fibrous 

 nest. 



PI. 11, Fig. 8 



Delaware Bay to Florida; West 



Indies 



GENUS CRENELLA Brown 1827 



Epidermis thick; umbones straight; 

 ligament small. These small mussels spin 

 a nest or else hide among roots of sea- 

 weeds and corals. They range in depth 

 from 0-300 fathoms. 



CRENELLA DIVARICATA Orbigny. Shell small, 

 equilateral; umbonal region high; delicate 

 ray-like ribs, a few of them curved; con- 

 centric sculpture also delicate causing 

 the ribs to appear slightly beaded; inner 

 edge crenate throughout; color brownish 

 yellow. Length 3 mm. 



North Carolina to West Indies 



CRENELLA GLANDULA Totten. Shell rounded 

 oval, rather swollen; umbones small, sep- 

 arated; minute concentric growth lines, 

 crossed by minute close together radiating 

 lines; epidermis brown or yellow; margin 

 toothed inside, pearly within. Length 12 

 mm. Range 3-60 fathoms. 



This is a mud dweller and is often 

 found in the stomachs of fish off Mass. 

 It is a pretty and oddly shaped little 

 shell. 



PI. 12, Fig. 8 



PI. 72, Fig. 10 



Labrador to North Carolina 



Family Dreissenlldae 



GENUS MYTILOPSIS Conrad 1857; 

 Congeria Partsch 1835 



Mantle of animal closed; byssal 

 opening small. Inhabits brackish water. 



MYTILOPSIS LEUCOPHAETA Conrad. Shell very 

 rough, incurved; epidermis brownish; ante- 

 rior end much depressed; hinge margins dug 

 out and with faint teeth. Length 18 mm. 



