BOREAL BATHYARK Arca frielei Friele, 1877: 2, ex Jeffreys MS; A. pectunculoides crenulata Verrill, 1882: 575. Shell subquadrate, longer than high, inflated. Dorsal margin straight, square at ends. Sculpture of broad, low commarginal ribs, overlain by fine radial striae. Hinge plate narrow; teeth small, 4-8 on each side. Periostracum thin, weakly hirsute; setae short, narrow. Length to 9 mm. Similar to the type species of the genus, B. pectunculoides, but having a more oblique outline; the teeth in the anterior series are twice the size of those in the posterior series, and the periostracum is coarser. F. R. Bernard (1979b) suggested that the oldest name for this species might be Arca raridentata S. V. Wood, 1840, from the Pliocene of England, but A. Warén (in letter) believes Wood's species is instead an older name for the eastern Atlantic Bentharca philippiana (Nyst, 1848). The relationship of B. frielei to the central Pacific B. imitata "var." (E. A. Smith, 1885) also merits investigation.
Throughout the Arctic, and Tufts Abyssal Plain (45.0°N, 153.9°W), in 5,180 m [LACM]. F. R. Bernard (1979b) reported specimens from the Beaufort Sea (71°N) [LACM], in 55 m.