Rorqual, the largest of the whale family, distinguished from the Greenland or right whale (baloena mysticetus, Linn.) by the presence of a dorsal fin, and by nearly parallel longitudinal folds extending between the arches of the lower jaw, from the under lip along the chest and abdomen. The name rorqual is of Norwegian origin, meaning "whale with folds;" the genus was named baloenoptera by Lacépède in 1804; the whalemen give to it the names of razorback and finback. There are no teeth, and the baleen or whalebone is very short. The largest species is the great northern rorqual (B. [physalus] boöps, Flem.), probably the most bulky and powerful of living animals. The head is about one fourth the length of the body, which is longer, more slender, and less cylindrical than in the right whale; the blubber is much thinner, rarely exceeding 6 in., and usually yields less than 10 barrels of oil, on which account, and also because the baleen is of comparatively little value, whalemen do not often attack this bold, restless, and powerful inhabitant of the ocean.

The head is so flat that the longest baleen plates seldom measure 4 ft.; there are many hundred plates, becoming toward the sides mere bristles; the posterior arch of the palate is large enough to admit a man, though the opening of the oesophagus would not allow anything larger than a cod to pass; the sieve is coarser and the swallow larger than in the right whale, indicating a totally different kind of food, the rorqual devouring not only medusas and crustaceans, but immense numbers of herring, pilchards, salmon, haddock, and cod; Desmoulins says that 600 good-sized cod, and a great quantity of pilchards, have been found in the stomach of a single individual. The longitudinal folds of the under surface vary in width from 1/2 in. to 3 in., and allow of the distention necessary to hold the water containing its prey, which is strained through the baleen during the shutting of the mouth; the tongue is free at the apex. The rorqual attains a length of 100 to 110 ft.; the body is compressed on the sides and angular on the back; the head comparatively small, and the tail narrower than in the right whale; the lower jaw is longer and much wider than the upper; there is a small dorsal opposite the vent; the pectorals are distant from the angle of the mouth, slender, straight, and pointed.

The color is dark bluish gray, lighter below, the lower lip and the folds rosy white. They blow so violently as to be heard a great distance in calm weather; when seen, they are almost always in motion, and when about to descend do not throw the tail high in the air. They are abundant in the arctic seas, especially on the coast of Spitzbergen, as far as lat. 80° N. in open summer weather; they generally avoid much ice, and are shunned by the right whale, and their appearance is consequently unfavorable to the whalemen's success. The usual rate of swimming is about 12 m. an hour; they are bold, but not revengeful or mischievous, though like other whales they will often attack and destroy a boat when their mates or young are wounded. The Greenlanders sometimes take small specimens by following in their canoes, and throwing so many lances that the animal dies from loss of blood; they are also occasionally stranded in their pursuit of herring and other fish into shallow water on a retreating tide.

In a skeleton 78 ft. long, the head was 21 ft., and the vertebral column 57 ft.; there were 7 cervicals and 13 dorsals, the longest rib (the 6th) 11 ft. long; the bodies of the larger vertebrae were 14 in. in diameter, and 6 to 7 ft. from tip to tip of the transverse processes; the skull in some parts had a vertical thickness of more than 3 ft. In a female 95 ft. long, the head was 22 ft. and the lower jaw 25 ft. long, and the weight of the skeleton 35 tons. This, with the Mediterranean rorqual (mentioned below) and other species, Gray places in a distinct genus physalus, though without very satisfactory generic characters. The lesser rorqual, considered by Bell as the young of the greater, was made into a separate species by Dr. Knox with the specific name of minor, and is the B. ros-trata (Gray). It attains a length of 25 ft., and has 15 fewer vertebras than the preceding species; the baleen is short and white, the folds of the throat rosy, and the upper part of the base of the pectoral is marked with a white spot.

It frequents the rocky bays of Greenland and the coasts of Norway and Iceland, sometimes descending to lower latitudes; it feeds on the arctic salmon and other fish; it is very active and rarely attacked, though its flesh is highly estimated in northern climates; the oil is also very delicate, and forms an important article of Icelandic materia medica.

Great Northern Rorqual (Balaenoptera boöps).

Great Northern Rorqual (Balaenoptera boöps).

The rorqual of the southern seas, or black whale of the South Pacific (B. australis, Cuv.), has a long dorsal immediately over the pectorals; it is black above, white beneath, and the folds roseous; the vertebrae are 52 in all. It rarely approaches the cape coasts, and from its strength, velocity, and small yield of oil is not considered worth pursuing; it attains a length of 40 ft.; it can leap entirely out of water, and is fond of floating perpendicularly, with only the head above the surface. The rorqual of the Mediterranean (B. antiquorum, Fisch.) is probably the one called mysticetus by Aristotle, and musculus by Pliny. Some of this species have been stranded on the southern coasts of France, 60 to 80 ft. in length; the color is grayish black above, lower jaw and folds rosy, rest of lower parts white. Two specimens of rorqual have been obtained within a few years on the New England coasts, and the skeleton of one 50 ft. long is in the collection of the Boston society of natural history. Other species are described. Some small species have been found fossil in the pliocene of Piedmont, far from and high above the present level of the sea.

M. Cortesi discovered two species, named by Desmoulins B. Cuvieri and B. Cortesii, respectively 21 and 12 ft. long.