The latter species often has been referred to as G. macrorhynchus.
Males are usually larger than females.
The coloration is black throughout, except for a white area often present below the chin. The head is swollen, so the forehead bulges above the upper jaw. The pectoral fin is narrow and tapering, and the dorsal fin is located just in front of the middle of the back. There are 7-11 teeth on each side of each jaw. During the colder months a population of this species remains in the Gulf Stream to the south of the Grand Banks of Newfoundland.