ness; the others diminish in regular gradation until those of the margin do not exceed 110th in length and a proportionate diameter. All the tentacles are of the same form; though this varies a little in different specimens, sometimes being blunt and nearly cylindrical, at others gradually tapering and drawn out to a fine point. They are pellucid, faintly tinged with flesh-colour, cream-yellow, or purplish, each one being always marked with from one to five pairs of lines or dashes of a dull-purplish colour, running down the two opposite sides to the tip. Those rows which form the marginal fringe are frequently divided into alternate patches of colour, a patch of pale tentacles, then one of purplish, six groups of each colour completing the circle. These alternations do not conceal the lateral marks of the tentacles, and though sometimes beautifully distinct, they are at others scarcely perceptible.
The surface of the disk is pellucid yellowish-white, marked with a circle of six squarish patches of opaque white, corresponding to the lighter portion of the marginal fringe: the lips are also opaque white.
This fine and very distinct species is exceedingly abundant in Weymouth Bay, extending from the deep water of the offing, even into the narrow harbour; but is never met with between tide-marks. It is, as its name imparts, parasitic in its habits, though not so strictly but that we frequently find specimens adhering to stones; and in captivity it is by no means uncommon for an individual to detach itself from its native site, and adhere to the bottom of the vessel, or even to crawl a little way up the perpendicular side. Gene-
