The Porpoise [Phocaena communis, or P. phocaena) is the smallest and most common of the Cetaceans found in the seas around the British Isles, and it also frequents the Scandinavian coasts, entering the Baltic in summer, and ranging as far north as Baffin’s Bay, and west to the shores of the United States. Southward it is met with as far as the Azores, and occasionally, though rarely, enters the Mediterranean. The Black Sea Porpoise has, however, been described as a distinct species, P. relicta. On the other hand, specimens similar to, if not specifically identical with, the ordinary Porpoise have been described from the mouth of the Rio de la Plata and the American coast of the North Pacific. The Porpoise is sociable and gregarious in its habits, being usually seen in small herds. It feeds on fishes, such as mackerel, pilchards, and herrings, of which it devours large quantities, and, following the shoals, is often caught by fishermen in their nets. It is represented in the building by the cast of a complete specimen taken on the Atlantic coast of North America, and also by the model of a head. Both were presented by the United States National Museum. Together with its immediate allies, the Porpoise differs from other members of the Dolphin family by the peculiar form of its teeth, which have spade-shaped instead of sharp and conical crowns. The external form is well shown in the American specimen and the accompanying illustration. The porpoise-hide of commerce is chiefly, if not entirely, White-whale skin; the skin of the porpoise itself being too thin and too oily to be of much use.
Although nearly related to the common species, the Indian Porpoise (Neomeris, or Neophocaena, phocaenoides) differs by the absence of a back-fin, and the smaller number of the teeth, which are also relatively larger. In size it is somewhat inferior to the Porpoise, and its colour is almost entirely black. The species is abundant off the coast of Bombay and Madras, and has also been met with off Japan, and in the Yang-tsi-kiang. The specimens exhibited include a female taken in the Yang-tsi-kiang, off Ichang, Central China, at a distance of nearly one thousand miles from the sea, and purchased in 1888; the skeleton of the same individual being also shown. There is also the cast of a smaller individual taken on the coast of Travancore, Madras, and presented by the Director of the Museum at Trivandrum in 1904. This cast shows very distinctly a depressed area in the middle of the back, in which the skin carries a number of minute horny scales, supposed to be the remnants of a bony and horny armour protecting the extinct Zeuglodonts.