we now know that there are ten or a dozen localities where it is found in large numbers, and that a fairly coarse clean sand and strong currents of clear water are conditions that it generally seeks. The peculiar odor, resembling that of iodine, which is a noticeable feature of the 'Amphioxus sand' in the Bay of Naples, was not recognized at any of the collecting places examined by us. Incidentally in our dredgings for Amphioxus, it was noticed that there are many sandy bottoms and beaches which are inhabited by large numbers of a rather small Balanoglossus. The western portion of Castle Harbor contains brain corals (Meandra) in great abundance, many of them attaining an enormous size and weight. The rocky shores, overgrown 
Fig. 27. The Sea Cat. (Tethys [Aplypia] dactylomela). X 1⁄3 with encrusting sea-weeds, are a favorite browsing place for the great opisthobranch mollusks (Aplysia), which the Bermudians call sea-cats (Fig. 27).
Off the south shore, at a distance varying from a few rods to a quarter of a mile, runs a rocky ledge,—a kind of barrier reef,-—over which the sea is breaking incessantly. Here and there the rocks take on the form of a huge bowl or crater (Fig. 28), from the rim of which the water pours over after each swell of the sea in a beautiful cascade. These diminutive atolls are known locally as 'the boilers.'
During almost every excursion through the northern lagoon there were encountered extensive patches of floating gulf weed (Sargassum), which, I may mention, grows at certain points along the south shore. An examination of the larger masses almost always yielded an abundance of various crabs, bryozoans and nudibranchs, some of the latter being most beautifully colored; frequently the less common fishes, such as the pipe fish (Syngnathus) and the grotesque Antennarius, were found in these floating islands, evidently their natural home. After protracted strong winds there are thrown upon the beach long windrows of gulf weed, which harbor a variety of the animals that live on the open sea. At such times the Portuguese man-of-war (Physalia) is frequently so abundant as to make the beach purple with its floats.
