Page:American Seashells (1954).djvu/432

350 terior of shell glossy-white with a faint trace of iridescence. Mantle open in front, and folded at the posterior end into a sessile excurrent siphon. Foot worm-shaped with a disk-shaped end. Hinge finely dentate. Crenella faba O. F. Miiller Arctic Seas to Nova Scotia. Faba Crenella Figure 75a Vi to Y2 inch in length, oval-oblong, with numerous radial ribs. Color reddish brown. Thin periostracum varnish-like. Byssus golden-brown. Com- mon offshore.

FiGtJRE 75. Crenella Clams, a, Cre?iella faba Miiller, Y^ inch (Arctic waters); b and c, Crenella glandula Totten, % inch (New England); d, Miisculus lateralis Say, % inch (Atlantic Coast) Crenella glandula Totten Labrador to North Carolina. Glandular Crenella Plate 28); figure 75b, c % to % inch in length, squarish, with the beaks near one corner. Radial ribs are fine, numerous, slightly beaded and often crossed by much finer, con- centric threads. Color olive-brown. A very common offshore, cold-water species. The smaller decussata has its beaks at the center of its more sym- metrical shell. Crenella decussata Montagu Decussate Crenella Bering Sea to San Pedro, California. Greenland to North Carolina. Less than % inch in size, oval, with numerous fine, decussated radial ribs. Color tan to yellowish gray. Dredged from 3 to 150 fathoms. A food of many marine fishes. Compare with glandula. Crenella divaricata Orbigny (North Carolina to southeast Florida and the West Indies) is even smaller than decussata, is pure white, and very in- flated.