Page:American Seashells (1954).djvu/556

458 458 Ajnerican Seashells of dark-brown periostracum. Concentric sculpture of distinct ridges. Color yellowish to brownish white. Uncommon in shallow water. Corbula barrattiajia C. B. Adams North Carolina to both sides of Florida and the West Indies Barratt's Corbula Figure 93a ^ inch in length, moderately compressed, rostrate at the posterior end, with poorly developed or without concentric ridges in the beak area. Right valve slightly larger than the left. The posterior end of the rostrum in the right valve projects far beyond that of the left valve. Color variable: white, pink, mauve, yellow, orange or reddish. Uncommon in shallow water to 50 fathoms.

Figure 93. Corbula clams, a, Corbula barrattiana C. B. Adams, Y^ inch (Atlantic Coast); b, Corbula swijtiana C. B. Adams, ^ inch (Atlantic Coast). Three views of each Swift's Corbula Figure 93b Corbula sioipiana C. B. Adams Massachusetts to east Florida and the West Indies. /4 inch in length, oblong, moderately obese; right valve larger, more obese and overlapping the left valve at the ventral posterior region. Posterior slope in the right valve bounded by 2 radial ridges, one of which is close to the margin of the valve. The left valve has only i ridge. Shell thick, with the posterior muscle scar on a slightly raised platform. External sculpture the same on each valve, consisting of irregular, concentric ridges. Color