34 



EAST COAST MARINE SHELLS 



PECTEN IBiBRICATDS Gmelln. Very flat, 

 trigonal in shape; hollow imbricated tu- 

 bercles regularly placed upon nine alter- 

 nating ribs; shell white, touched with 

 pink or red, interior margin and hinge 

 area purple, center yellow. Length 25 mm. 



Single valves have been taken near 

 the Yamato rocks, south of Palm Beach, 

 Florida and it apparently lives off the 

 Florida Keys. 



PI. 8, Fig. 2 



Florida Keys and West Indies 



SDBGENDS AEQOIPECTEN Fischer 1886 



PECTEN HELIACDS Dall. Shell of moderate 

 size, mottled and zoned with pink or crim- 

 son upon a white surface; ribs about twen- 

 ty, narrow, nearly keeled, interspaces 

 wider; valves equal, inequilateral, notch 

 wide and shallow; right valve paler than 

 left; pointed scales on top of ribs visi- 

 ble under a glass; interior clouded with 

 brownish purple and grooved to match out- 

 Side ribs. Length 40 mm. 



PI. 9, Fig. 5 



Southern Florida to West Indies 



PECTEN ACANTHODES Dall. Shell subclrcu- 

 lar, olive brown with paler mottlings; 

 twenty-two minutely spinose ribs, the 

 spines in three subequal rows, with two to 

 three smaller prickly threads In the nar- 

 row interspaces; ears subequal, the ante- 

 rior slightly larger, both with about five 

 threads; hinge line cross-striated; height 

 Z2 mm., width 32 mm. 



Compared with P. exasperatus this 

 shell is less Inflated, wider and with 

 less prominent spines. 



PI. 9, Fig. 3 



Southern Florida to West Indies 



SECTION PLAGIOCTENIUM Dall 1898 



PECTEN IRRADIANS Lamarck. A large thin- 

 shelled form, gray and white, rarely yel- 

 low brown or red, generally purplish near 

 hinge; ribs seventeen to twenty; acutely 

 scalloped upon basal margin; ears two 

 thirds length of the shell, notch forming 

 acute angle or narrow slit. Height 2.6 

 Inches. 



Most abundant in the north, espe- 

 cially on the New Jersey coast where large 

 numbers are gathered for the markets. 



PI. 7, Fig. 7 



PI. 72, Fig. 11 



Nova Scotia to Florida and Texas 



PECTEN IRRADIANS CONCENTRICA Say. More 

 Inflated and solid than the preceding; 

 ribs seventeen; lower valve yellowish, up- 

 per blue-gray; interior of valves white, 

 sometimes with brown blotches. Length of 

 adult, parallel to hinge line, slightly 

 under 1 inch. 



New Jersey to South Carolina 



PECTEN NUCLEUS Born. Nut Scallop. A thin, 

 small shell variegated with gray, white and 

 dark brown; twenty-one to twenty-three 

 ribs. It attaches itself to soft objects 

 rather than hard ones. Length 30 mm. 



PI. 9, Fig. 1 



Florida Keys to Venezuela 



PECTEN GIBBUS Linn§. Humped Scallop. The 

 ribs range from eighteen to twenty-three 

 and are rather rough; lower valve more 

 ventricose than the upper; ears nearly 

 equal in size, striated and obtuse. 



The color forms are; a delicate 

 pink mottled with brown, light blue mot- 

 tled with dark brown and touches of white 

 and yellow, also other combinations. Red 

 examples are infrequent. 1.5 inches. 



An abundant shallow water form, 

 very variable in its color manifestations 

 but never attaining the size of its north- 

 ern brethern. 



PI. 9, Fig. 2 



PI. 7, Fig. 6 



North Carolina to the West Indies 



PECTEN GIBBUS AMPLICOSTATUS Dall. Many- 

 ribbed Scallop. A larger and heavier shell 

 than the preceding one; ribs twelve to fif- 

 teen; lower valve white, the upper gray. 



PI. 8, Fig. 1 



Texas to Columbia, South America 



SUBGENUS LYROPECTEN Conrad 1862; 

 Nodopecten Dall 1898 



PECTEN NODOSUS Linne. Knotty Scallop. 

 Valves nearly equal in size; entire sur- 

 face covered with whitish radiating ribs, 

 divided into about ten raised knob areas 

 with smaller zones between; interior with 

 excavated channels corresponding to ele- 

 vated areas outside, reddish brown within 



