^N. cara.^ This species is found on the New England coast. The members of the community are arranged along a hollow stem about three inches long which opens into every individual. At the top of the stem is a sac, or float; just below this is a group of swimming-bells which have no manubrium or mouth, and whose sole function is to provide locomotion for the community; and below these are three sets of zoöids, each having a triangular shield and tentacles. The tentacles are longer than the main stem. One of these last groups consists of the nutritive members, the mouths of the community, resembling manubriums of swimming-bells out of place. Each one has at the point of attachment a bunch of long, delicate tentacles having pendent knobs of lasso-cells. A second group, also with mouths, has shorter tentacles which are carried in spiral coils. The members of the third group have but one tentacle each and resemble the float at the end of the stem; presumably these drop off and produce new colonies. There are also on the lower part of the stem other reproductive members, which resemble the clusters of buds seen on [pg131] tubularian hydroids. These animals are pink in color and move through the water with a graceful swaying motion. GENUS ^Physalia^ [Illustration: /Physalia arethusa/; Portuguese man-of-war, one fifth natural size.] ^P. arethusa^, the Portuguese man-of-war. This colony is perhaps the best-known one of the group, since it attracts much attention in Southern waters, and is also one of the most remarkable examples of an animal community. The most prominent part of the compound body is the float, an oblong pear-shaped bag, full of air, which floats on the surface of the water. Its color is bright blue, varying to rose. On the upper side of this air-vessel is a crest, or sail, and from the under side depend long tentacles, or streamers. Some of these tentacles are covered with stinging- or lasso-cells; some are the feeding zoöids, with flask-shaped bodies, and some, which look like bunches of grapes, are the reproductive zoöids. The tentacles in this curious cluster are all close together and hang from one side of the float, near the broader end. The longest are on the outside, which may be called the windward side, since they serve to keep the crest, or sail, before the wind; and when the wind is strong they stretch out to a remarkable length,—forty to fifty feet,—acting as anchors to keep the colony from being driven ashore. They also change its course by raising the pointed end of the float, thus forcing it to "come about." These long tentacles, ordinarily carried more or less curled up, are in bunches of two to four, and emerge from a common stem. Clusters of similar, but smaller, tentacles alternate with the larger ones, but grow somewhat nearer the pointed end of the float; these are purely locomotive organs. Next come two smaller