MARINE UNIVALVES The Olive Shells. Rice Shells. Harp Shells border, and the same wavy edge is shown by the ribs, and the undulating pattern that decorates the spaces between. The width of the ribs is usually unequal, but the greatest number of them are quite narrow; the crenations form a series of spinous tubercles. Colour, blue gray, festooned between ribs with black. Ribs, chestnut, banded on pale ground. Found in muddy sand in deep water. Length, 2 to 4 inches.
Habitat.— Panama.
The Slender Harp (H. gracilis, Brod. and Sby.) is least of all and slim, with flat ribs far apart, delicately semi-transparent, and tinted and variegated with gray and rose, accented with bright red hair lines. Length, inches.
Habitat.— Polynesia.
The Lesser Harp (H. minor, Lam.) is slightly larger than H.
gracilis, more square shouldered, decidedly darker. The narrow ribs are crossed with black lines in pairs. Wavy longitudinal markings of brown streak the spaces between ribs.
Habitat.—Indian Ocean.
The Conoid Harp (H. conoidalis, Lam.) is the most variable species. Its elevated spire and broad sloping shoulders, are con stant characters. The ribs are narrow, rounded and distant. The colour scheme is brown in many shades, the pattern like the banding of an agate, crossing the ribs and festooning the inter stices. Often the patterns are blurred, but the effect is very rich. Length, 3 to 4 inches.
Habitat.— Mauritius, Indian Ocean, Philippines.
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