The Sea-Pens, or Pennatulæ, are remarkable from the circumstance that, although they possess an internal calcareous support, they are not permanently attached to foreign bodies. The lower portion of the stem, which strikingly resembles the barrel of a quill, is naked, and, when found in the bays upon our coast, is generally stuck into the mud at the bottom like a pen into an inkstand, whilst the upper two thirds of the stem are feathered with long closely set pinnæ, comparable to the barbs of a quill, from the margin of which are protruded the rows of polyps which minister to the support of the common body of the compound animal. The purple-red _Pennatula phosphorea_, which is found in great plenty sticking to the baits on the fishermen's lines, especially when they use muscles to bait their hooks, is one of the most singular and elegant of the British sea-pens. Some authors believe that it is capable of using its fin-like arms like oars, but observations are wanting in corroboration. The pale orange fawn _Virgularia mirabilis_, an allied species, has a more elongated slender form than the pennatula. Its rod-like body, from six to ten inches long, is furnished with short fin-like lobes of a crescent shape, which approach in pairs, but are not strictly opposite; they are about the eighth of an inch asunder, and are furnished along the margins with a row of urn-shaped polyp-cells. These very delicate and brittle animals seem to be confined to a small circumscribed part of the coast, which has a considerable depth and a muddy bottom, and the fishermen accustomed to dredge at that place believe from the cleanness of the Virgulariæ, when brought to the surface, that they stand erect at the bottom with one end fixed in the mud or clay. [Illustration: Grey Sea-Pen.] [Illustration: Virgularia mirabilis.]