_Cirri._--The first pair is placed near the second pair, and is of considerable length; the second has the anterior ramus thicker than the posterior ramus, and the segments brush-like; the segments (Pl. X, fig. 26) of the four posterior cirri bear from four to six pair of long spines, with a row of small intermediate spines: in the posterior cirri of _L. australis_ the lateral rim spines are much developed; and in those of _L. fascicularis_, the usual pairs of large spines are lost in a broad triangular brush, formed by the increase of the lateral marginal, and intermediate spines. _Caudal Appendages_ (Pl. X, fig. 18 _b_), very small, either blunt or pointed, and quite destitute of spines. The prosoma is well developed. The stomach is surrounded in the upper part by a circle of large branching cæca. The generative system is highly developed; the testes coating the whole of the stomach, entering the filamentary appendages and the pedicels of the cirri; the two ovigerous lamellæ contain a vast number of ova; they are united to rather large fræna, of which the sinuous margin supports either a continuous row or separate tufts of glands. _Distribution._--The species abound over the arctic, temperate and tropical parts of the Atlantic, Indian and Pacific Oceans, and are always, or nearly always, attached to floating objects, dead or alive. The same species have enormous ranges; in proof of which I may mention that of the six known species, five are found nearly all over the world, including the British coast; and the one not found on our shores, the _L. australis_, apparently inhabits the whole circumference of the southern ocean.