[Illustration: FIG. 2.--One of the polyps of Rhabdopleura which is attached by its soft contractile stalk (c) to the dark internal cord seen in Fig. 1. A similar polyp issues during life from the open end of each of the upright tubes seen in Fig. 1, and is, when disturbed, pulled back into the tube by the contraction of the cord c. a, mouth; b, vent; c, contractile stalk; d, head-shield or disk; e, the left gill-plane; f, the body-mass enclosing the intestine, etc. (From a drawing made by the author in Lervik, Stordö, in 1882.) For a full account of Rhabdopleura, see the "Quart. Journal of Microscopical Science," vol. xxiv., 1884.] We filled glass jars with sea water and placed the bits of coral in them, and I eagerly examined them for the creeper-like "Rhabdopleura." There, sure enough, it was on several of the dead stems of coral, and we sailed back to Lervik with our booty in order to examine it at leisure with the microscope whilst still fresh and living. In our temporary laboratory at the farmhouse the little polyp which it had been my chief object to study, issued slowly from its delicate tubes when placed in a shallow trough of sea-water beneath the microscope. I was able on that day, and many others subsequently--with renewed supplies from the depths of the fiord--to make coloured drawings of it, and to find out a great deal of interest to zoologists about its structure. The minute thing (Fig. 2) was spotted with orange and black like a leopard, and had a plume of tentacles on each side of its mouth, which was overhung by a mobile disk--the organ by means of which it creeps slowly out of its tube, and also by which the transparent rings which form the tube are secreted and added one by one to the tube's mouth, so as to increase its length. The creature within the tree-like branching system of tubes (Fig. 1) is also tree-like and branching, fifty or more polyp-like individuals terminating its branches and issuing each from one of the upstanding terminal branches of the tube system. I was able to determine the "law" of its budding and branching, and I also found the testis full of spermatozoa in several of the polyps, but I failed to find eggs. I believe that we were too late in the season for them; and they are still unknown.