EAST COAST MARINE SHELLS 



55 



VENUS CAMPECHIENSIS Gmelln. A larger, 

 rounder, much thicker shell than V. mer- 

 cenarla, usually white both inside and out; 

 lower posterior angle of the pallial line 

 more acute, scalloping of inner margin fin- 

 er, arrangement of cardinal teeth less fan- 

 like. Length 4 inches. 



The juvenile shell is less convex 

 than in the other species, lunule and es- 

 cutcheon brown with fine pale zigzag lines. 



Inside the margin is invariably 

 white but occasionally in the umbones cav- 

 ity a pale purple tinge is present. The 

 latter is entirely absent in V. mercenaria. 

 The brown zigzag marks are in the form of 

 lines which in V. mercenaria are broader 

 and inclined to be blotchy. 



The mutations are similar to those 

 in V. mercenaria except that the center of 

 the disk is never entirely smooth. Some- 

 times a trace of purple may be found at the 

 margin which may stjggest interbreeding 

 with V. mercenaria. 



Beyond the Mississippi delta and 

 especially in Texas this is the persistent 

 type. It is also abundant in Yucatan. 



PI. SI, Fig. 2 



Chesapeake Bay to Cuba; Texas; 



Yucatan 



VENDS CAMPECHIENSIS ALBORADIATA Sowerby. 

 Brown rays on a pale ground characterize 

 this race. 



Gulf of Mexico 



VENUS CAMPECHIENSIS QUADRATA Dall. Shell 

 thin, small, subquadrate, uncolored. 



VENUS CAMPECHIENSIS TEXANA Dall. Concentric 

 lines toward center of disk coalescent, the 

 ribs flat-topped with polished tops; valves 

 usually extremely convex. 

 Texas 



GENUS ANOMALOCARDIA Schumacher 1817 



Valves rostrate or pointed at end; 

 inner edge crenulate; ligament exposed; 

 three cardinal teeth in each valve; con- 

 centric sculpture the strongest. 



ANOMALOCARDIA BRASILIANA Gmelln. Umbones 

 elevated and angulated; major portion of 

 surface smooth; posterior angle beaded in 

 upper portion. 



The common Anomalocardla of the 



West Indies. It is very variable both in 

 form and color pattern. Length 21 mm. 



PI. 21, Fig. 8 



Cape Hatteras, North Carolina to 



West Indies; Brazil 



ANOMALOCARDIA CUNEIMERIS Conrad. Similar 

 to the preceding but surface smooth and 

 with rather round concentric ribs; lunule 

 and dorsal area livid color. Length 17 mm. 



PI. 21, Fig. 7 



Lake Worth, Florida; southward on 



shores of continent to U. S. of 



Columbia 



GENUS GEMMA Deshayes 1853 



Shell minute, animal characterized 

 by vivaparity. The young are carried for a 

 considerable time before being produced 

 alive. 



The shells are usually purple but 

 sometimes white. They live in mud or sand 

 on both of our coasts, Atlantic and Pacific, 

 and have not been taken in any other re- 

 gions. 



GEMMA GEMMA Totten. Rounded-trigonal in 

 shape, external sculpture irregular, spac- 

 es between sulci varying in width. 



Southern examples show relatively 

 strong and regular sculpture. Length 4 mm. 



PI. 18, Fig. 7 



Labrador to North Carolina 



GEMMA PURPUREA Lea. More compressed than 

 adult G. gemma, generally paler and often 



white, more triangular, 

 less f-ull, not so 

 elongated, vihite in- 

 stead of purple. Length 

 2.8 mm. 



Fig. 54 



Fig. 54 Massachusetts 



Gemma purpiirea . „ 



2.8 mm. ^° Texas 



GENUS PARASTARTE Conrad 1862 



Shell minute, heavy, umbones prom- 

 inent and elevated; shell equilateral, 

 equivalve; lunule large, ligament short; 

 surface smooth; color purple and white, in- 

 ner margin toothed; one strong and two 

 faint cardinal teeth in right valve; two 

 strong cardinal teeth in left valve. 



It appears superficially near 



