Nuculana collinsoni: Shell small, inflated, slightly inequilateral, olivaceous in the young, tending to a dark brownish tint in the adult, the periostracum strong, minutely evenly vermiculately wrinkled all over; anterior end shorter, evenly rounded; posterior . portion with a rounded ridge extending to the posterior extremity where it forms a rounded point, the shell being compressed above and below this ridge and the margin below slightly incurved and retractively obliquely truncate; the basal margin is slightly rounded; there is a small lanceolate impressed area in front of the low, slightly opisthocoelous beaks, and a large one behind them, but there is no circumscribed lunule or escutcheon; the interior is white, there is a large triangular resilifer below the beaks and eleven anterior and eight posterior hinge teeth;- no indications of a pallial sinus appear on the specimens but the adductor scars are large and conspicuous. Height of specimen 6; length 8.5; diameter 4 mm.

Shell subequilateral, inflated, subquadrate; posterior end attenuate, pointed, generally set off by oblique sulcus. Sulpture absent, or of obscure commarginal growth lines. Periostracum dark brown, dull to silky, with minute, wavy commarginal striae. Length to 20 mm.
This species has an extremely variable outline. Portlandia collinsoni (Dall, 1919), described from the Arctic coast of Alaska (70°N, 144°W), chiefly distinguished by wrinkles on the periostracum, falls within the range of variation. A commensal hydroid often attaches to the shells of this species. Lubinsky (1980: 20-21) has shown that P. sulcifera (Reeve, 1855), described from the Canadian Arctic, is a distinct species, with both unique anatomical and shell structure differences.

Nuculana collinsoni: This is a remarkable little shell, quite distinct from its nearest relatives. It is of the same general type as Leda (Portlandia) arctica Gray, but much shortened up, smaller and more acute behind in proportion to its size. The curious vermiculation of the surface is probably in great part if not entirely a function of the periostracum.

Nuculana collinsoni: Off Collinson point, Alaskan Arctic coast, in three fathoms, -sandy bottom.