_Elminius Kingii._--The cement-glands here resemble those of Chelonobia, but the trunk does not seem to be enlarged before entering the gland. The glands are situated rather far apart; and the chief peculiarity is, that the trunk connecting the glands is as tortuous as the track of a worm. Each gland gives out two ducts, which bifurcate repeatedly, and often inosculate, making, in parts, an hexagonal mesh-work: some of the branches do not debouch on the basal membrane, but terminate in blunt points. So numerous are the ducts, that the basal membrane may be compared to pieces of paper with the fine fibrous branching roots of some plant dried and heaped on it. Some of these ducts are very regularly jointed, and resemble a conferva,--an appearance which I believe is owing to divisions in the contained cement; other ducts are partially marked by little wrinkles, as presently to be described under Balanus. The cement, instead of, as heretofore, invariably forming a slip round and beneath the circumference of the basal membrane, here often forms little, independent, circular, and irregularly-shaped discs, each of which has issued from a single orifice. I may here add that in two species of _Tetraclita_ I saw the cement-ducts repeatedly bifurcating, with some of the branches inosculating, as in Elminius and Chelonobia. In _Balanus balanoides_, which, like all the Cirripedes hitherto mentioned, has a membranous basis, I could only make out an amazing number of bifurcating and inosculating cement-ducts, of very various diameters. The cement-tissue, on the under side of the basal membrane, generally consisted of little circular discs, on an average from 2 to 5/1000ths of an inch in diameter; but there were also globules and short tortuous threads of cement. In some very much elongated and crowded specimens--in which, during the downward growth of the walls, the basal membrane had ceased to reach the surface of attachment, and being thus suspended had become, as viewed from the outside, deeply concave--the cement had apparently continued to try to reach the rock, and now hung down in the form of two thickish roots, some tenths of an inch in length. These roots were round, and tapered either to a fine or blunt point; one was doubled on itself, and so had become united; in the other, I could perceive five layers or sheaths of the cement-tissue, one within the other; the innermost of these layers, which once, no doubt, formed the outside surface of the root, was only a quarter of its present length.