As Myonera demistriata:
Shell elongate, 12 or 13 radial ribs present anterior to rostrum on posterior region of shell extending from umbo to ventral margin, each rib is sharp and terminates in a point at ventral margin; seven or eight form main ribs with five faint radial ribs present posterior to main ribs, the most posterior forms ventral limit of the rostrum; oblique rostrum traversed by numerous concentric growth lines and one or two incomplete, longitudinal striae; 11-15 low, rounded concentric undulations present anterior to main ribs; no hinge teeth present; resilifer almost central, slightly elongate posteriorly; resilium triangular.
B. hadalis is similar to B. tillamookensis Dall (1910)in that it has anterior concentric sculpture, and several posterior radial striae. It differs in that B. tillamookensis has no longitudinal striae on the rostrum, the latter being wide, rounded and triangular. The ventral margin is more sinuous than in B. tillamookensis. Maximum shell measurements are: length, 9.1 mm; height, 5.3 mm.

Northwest Atlantic off the east coast of North America. Depth range: 1135-3917 m.