The location of the first dorsal fin above the pelvics instead of about midway between the latter and the pectorals, and the very different shape of its tail fin (cf. fig. 23 with fig. 21), are the most conspicuous field marks separating this shark from the Greenland shark. Brucus also differs from the latter in that the teeth are alike in the two jaws, instead of unlike, and that the skin of its back and sides is sparsely strewn with large scales with either one or two sharp points.[page 57]
Described as dark gray, olive or brown above, with metallic reflections, and with or without darker blotches; as paler brown or gray to white below. The scales have been described as luminescent, but there are no special luminous organs.
The largest of which we have found a record (a specimen from British waters) was 9 feet long. One 8 feet 4 inches long weighed about 300 pounds.
Eastern Atlantic (including the Mediterranean) from tropical West Africa to Ireland and the North Sea, and accidental in the western Atlantic; represented in South Africa; off California; in the Hawaiian, Japanese, and Australo-New Zealand regions, and in Arabian waters by forms that probably cannot be distinguished from brucus of the Atlantic.
A single specimen of this little known shark came ashore at Provincetown in December 1878. This and one taken near Buenos Aires more recently are the only records of it from the western Atlantic.