(Bean in Thorpe, 1844)
Description (shell):
Elongate oval, about two and a half times long as broad. Highly arched, with distinct sharp keel and pronounced beaks. Sculpture of coarse granules, in longitudinal series, particularly marked laterally, and on head valve and tail valve, where they are developed as protruding tubercles. Girdle narrow, covered with small, flat scales interspersed with fine, recumbent spines; fringed with similar spines (H. hanleyi-detail).
Size:
Up to 22 mm long.
Colour:
Shell valves off-white to yellowish.
Habitat:
Lower shore and sublittoral.
Distribution:
Northern coasts only (Distr. H. hanleyi).