Body sub-conical, with a dorsal and ventral ridge: head obtuse, about one-seventh of the entire length.
M. Monoceros, Scoresby, Arct. Reg. vol. i. p. 486. pl. 15. Flem. Brit. An. p. 37. Small-headed Narwhal, Flem. in Wern. Mem. vol. i. p. 131. pl. 6.
Entire length, exclusive of the tusk, thirteen to sixteen feet; circumference (at the thickest part) eight to nine feet; length of the tusk about five feet*.
Anterior half of the body nearly cylindrical; posterior half conical: this latter portion furnished with a dorsal and ventral ridge, which take their origin about three feet from the extremity, and extend half way across the tail; the edges of the tail run in like manner six or eight inches along the body, forming ridges on the sides of the rump: head about one-seventh of the entire length; small, blunt, and round; the forehead very prominent, rising suddenly from the snout: mouth small; intermaxillary bones furnished each with one tooth directed forwards; in the female these teeth generally remain through life concealed in the sockets, not appearing externally; in the male, that on the left side is exserted, growing to the length of several feet; it is spirally striated from right to left, nearly straight, and tapering to a round blunt point; very rarely, in this last sex both teeth are equally developed, and both exserted: blow-hole semicircular, situate directly over the eyes: pectoral fins short: no dorsal fin, but instead of it an irregular sharpish fatty ridge, two inches in height, extending two feet and a half along the back, nearly midway between the snout and the tail: tail divided by a notch into two lobes, which project laterally and are somewhat pointed. Prevailing colour white, or yellowish white, with dark gray or blackish spots of different degrees of intensity.
* The above measurements are from Scoresby, from whose excellent work on the Arctic Regions much assistance has been derived in drawing up the characters of this species, as well as of some others of the Cetacea.
Has only occurred hitherto in two or three instances on the British shores. In the Northern seas is said to be gregarious; each sex herding separately. Feeds on sepice and other molluscous animals.