Footnote 19: Unfortunately all the female porpoises died at the time Dr. Townsend’s paper was passing through the press. R. C. A. Our porpoises were heavy feeders, the five consuming about ninety pounds of fresh fish a day. This quantity of food has kept them in good condition, apparently without loss of weight. For several days after their arrival they would eat nothing, but at the end of a week they began to take live fishes and, after having once started to feed, it was not difficult to get them to take dead fish. A few days of hunger brought them around, as it does in the case of the newly captured seal or sea lion. Their principal food is herring and tomcod purchased in the markets. The live crabs thrown to them at various times were quickly seized and much tossed about, but were not eaten. The keeping of porpoises in captivity has presented some difficulties with the water supply, their excrement constantly discoloring the water. The pool cannot be drained empty and cleaned, like those used for seals, as stranded, and consequently frightened, porpoises beat the ground with their tails so violently that they would be injured by the daily emptying of the pool. The water is now being kept fairly clear by carrying extra pipe lines to the pool and greatly increasing the flow of water. The pool is supplied with brackish and rather impure water pumped from New York Harbor, as it is not practicable to supply it with pure sea water from the Aquarium’s large storage reservoir, on account of the fact that porpoises would rapidly discolor the stored sea water which is so important to the health of the collection of marine fishes in the Aquarium. The necessity of keeping them in the water of the Harbor, and exhibiting them in a public exhibition room which has to be heated during the winter makes it, of course, impossible to hold them under entirely favorable conditions, yet they are undoubtedly doing well. They could no doubt be kept for some time in fresh water, as is sometimes done with seals and sea lions, but they would eventually suffer from the lack of the salts contained in sea water. Porpoises, perhaps of this species, frequently enter the fresh waters of Pamlico Sound through the inlets southwest of Hatteras, and many species of marine porpoises make long journeys into the fresh waters of rivers. CHAPTER XXV THE BLACKFISH The blackfish, the most gregarious and one of the largest members of the porpoise family, is sometimes called the “pilot whale” because it blindly follows a leader and the herds can be driven almost like a flock of sheep. Several species have been recognized in different oceans of the world, but the most common and widely distributed is the one called by naturalists _Globicephalus melas_, which occurs in great schools on both sides of the North Atlantic.