EAST COAST MARINE SHELLS 



107 



CERITHIDEA COSTATA Da Costa. Shell narrov/- 

 ly elongated, many rounded longitudinal 

 ribs, beaded more or less by spiral rib- 

 lets; suture well marked; color dark brown 

 and often white banded. Length 15 mm. 



PI. 38, Fig. 9 



Tampa Bay to Florida Keys 



CERITHIDEA lOSTOMA Pfeiffer. Strongly 

 ribbed and varicose, spirally striate, 

 chocolate brown with narrow whibe central 

 band. Length 22 mm. 



A narrower shell than C. scalari- 

 formis. 



South Carolina to Texas; West Indies 



CERITHIDEA SCALARIFORMIS Say. Color vary- 

 ing from whitish through light fawn to cho- 

 colate, with contrasting dark or light 

 lines; suture well impressed and marked by 

 a narrow thread; riblets closely placed, 

 spiral riblets less distinct. Upon the 

 base of the last whorl there are exclusive- 

 ly spiral riblets. Length 1 inch. It is a 

 rather common shell on the Florida Keys, 

 living near high-tide mark. 



PI. 43, Fig. 7 



Georgia to Florida and Texas 



CERITHIDEA TURRITA Stearns. A rather thin 

 little shell, varying from white to choco- 

 late color with a feeble central line; ribs 

 numerous upon the convex whorls; suture 

 deeply grooved. Length 10 mm. 



PI. 38, Fig. 16 



West coast of Florida to Texas 



GENUS BITTIUM Leach 1847 



Shell elevated and with granular 

 whorls; Inner lip simple; outer lip not re- 

 flected. Small shells living mostly In 

 temperate seas. 



BITTIUM ALTERNATUM Say (Bittium nigrum Tot- 

 ten). Shell small, covered with a network 

 of raised lines; color gray or slate; upon 

 upper whorls, lower ones usually much light- 

 er; whorls six to eight; aperture oblique, 

 rounded and flaring, canal a mere notch; 

 operculum horny with four to five spiral 

 turns. Length 5-10 mm. 



Common on eelgrass at Nantucket and 

 New Bedford, elsewhere on seaweed and 

 stones. The young are sometimes so plenti- 

 ful that the sand is not visible between 

 them. These are very dark in color and ap- 



parently reach maturity the second season. 

 PI. 38, Fig. 14 

 PI. 71, Fig. 3t 



Prince Edward Island; Massachusetts 

 Bay to North Carolina 



SECTION DIOSTOMA Deshayes 1850 



BITTIUM VARIUM Pfeiffer. Thin, diaphanous, 

 grayish brown; plications lacking upon low- 

 er portion of body whorl, that portion some- 

 what varicose. Length 5 mm. 



It has been taken abundantly in the 

 Metacumbe region of the Florida Keys; also 

 at Palm Beach, Florida. 



PI. 38, Fig. 27 



Virginia to Florida, Texas; West 



Indies 



SECTION STYLIFERINA A. Adams 1860 



BITTIUM ADAMSI D&ll . Opaque white with a 

 brown tint on early whorls; nine rounded 

 whorls; nucleus acute and sculpture reticu- 

 late; varices few, base imperforate, no 

 trace of notch anteriorly. Length 3 mm. 



North Carolina to Florida and West 



Indies 



SECTION ALABINA Dall 1902; Elachista 

 Ball 1901 



BITTIUM CERITHIDIOIDES Dall. Smaller than 

 the preceding and more elegant; nucleus of 

 three whorls and seven more following; 

 translucent with delicate brown painting; 

 nucleus pale and glassy; at least thirty 

 fine regular concavely arched riblets ar- 

 ranged transversely. 



Dall states in his description that 

 it suggests a minute Cerithidea with an im- 

 perfect lip and a faint varix. Length 3 mm. 



PI. 38, Fig. 25 



North Carolina to the West Indies 



Family Aporrhaldae 



GENUS APORRHAIS Dillwyn 1823 

 (PELICAN'S FOOT) 



Spire long; aperture long and nar- 

 row, ending in a straight canal in front 

 and a channel extending up the spire; outer 

 lip dilated and heavily thickened. 



APORRHAIS OCCIDENTALIS Beck. Western Peli- 

 can's Foot. Easily recognized by the 



