54 



EAST COAST MAPJNE SHELLS 



shell with concentric sculpture forming 

 deep grooves; umbones well elevated; hinge 

 strong; ends somewhat pointed. Length 3 

 inches. 



PI. £0, Fig. 8 



Florida Keys; Texas; West Indies 



CHIONE SUBROSTRATA Lamarck (C. beaiii Reel.). 

 Concentric ridges more numerous than in C. 

 cancellata and more truncated; zigzag mark- 

 ings of darker shade than ground color. 

 Length 25 mm. 



Southern Florida to Brazil 



SECTION TIMOCLEA Brown 1827 



Radial sculpture the strongest, 

 concentric lines faint; middle left and two 

 posterior right cardinal teeth grooved. 



CHIONE GRANULATA Gmelln. Radiating ribs 

 crossed by scales which are not continued 

 in the interstices; markings dark and vari- 

 egated; interior purplish at posterior end 

 and near margin. Length 25 mm. 



PI. 18, Fig. 12 



Florida Keys to Brazil 



CHIONE PYGUAEA Lamarck. Shell compressed, 

 oval, resembling a miniatiire C. reticulata 

 but longer and flatter; hinge area wide, 

 hollow, smooth in one valve and marked with 

 prominent black transverse lines; lunule 

 impressed. Length 13 mm. 



PI. 20, Fig. 5 



Florida Keys (reefs); West Indies 



SECTION LIROPHORA Conrad 1863 



Broad concentric waves very promi- 

 nent, radially striate; ligament not cov- 

 ered by edge of valve. 



CHIONE LATILIRATA Conrad 

 Shell triangular, swollen, solid; lunule 

 sunken so that portion of shell enclosing 

 it is incurved; strong concentric ribs fur- 

 rowed on upper side and almost smooth over 

 anterior three fourths of shell; color 

 dirty white, marked with brown and with an 

 indication of rays; very small palllal 

 sinus. Length 1.5 inches. 



Both old and fairly fresh valves 

 have been taken in Palm Beach County, 

 Florida, Frequent in the Pliocene beds of 

 Florida. 



PI. 75, Fig. 13 



Palm Beach, Florida to the West 



Indies 



GENUS VENUS Linn6 1758 



Shell large, earthy, trigonal in 

 shape; lunule v/ell marked; interior margin 

 crenulate; ligament strong and exposed. 



VENUS MERCENARIA Linng. Shell solid; um- 

 bones far forward and projecting nearly to 

 front of shell, also elevated and curved; 

 lunule rough and heart-shaped; blunt point 

 at posterior end of shell; ridges crowded 

 and most conspicuous at ends; Interior 

 white, often deep violet outside the mus- 

 cular Impressions; basal and interior mar- 

 gin crenulated. Length 3 inches or more. 



This the common hard-shell clam 

 of commerce is Icnown "down east" as Quahog. 

 From the purple edge of the shell the 

 aborigines made their purple wampum v/hile 

 the white was manufactured from various 

 other species. 



There are many mutations of this 

 species, some of the forms hardly deserv- 

 ing separate names. These are produced by 

 various agencies among which might be men- 

 tioned the temperature, food, kind of bot- 

 tom and salinity of the water. 



In the Pleistocene fossil beds of 

 Sankoty Head, Nantucket Island there are 

 shells remarkable for their variety. Some 

 of these are without parallel among the re- 

 cent species. 



PI. 21, Fig. 6 



Nova Scotia to Yucatan 



VENUS MERCENARIA NOTATA Say. In addition 

 to the usual characters this form exhibits 

 zigzag brown painting and usually lacks the 

 purple coloring inside. 



PI. 21, Fig. S 



Massachusetts to Florida 



VENUS MERCENARIA ALBA Dall. Purple colora- 

 tion absent, no brown markings as in the 

 preceding form. 



VENUS MERCENARIA SUBRADIATA Palmer. The 

 smooth middle portion of the disk shows 

 fine and even radial lines between the 

 concentric ones. 



The two latter forms are found as- 

 sociated with the typical. 



