-------- AUGUBRA (?) Chenu. Illust. Conch., Tab. 4, fig. 2.
Shell dirty white, rugged and massive: alæ thick, with their sutural edges coarsely crenated.
Hab.—Algoa Bay, Cape of Good Hope. Attached to littoral rocks; often associated with [Balanus Capensis] and [Chthamalus dentatus]; Mus. Brit., Cuming, Stutchbury, Bowerbank.
General Appearance and Structure of Shell.—Shell extremely rugged, irregular, massive, generally much corroded, steeply conical or even sub-cylindrical: orifice large, broad, rhomboidal, of nearly equal breadth at both ends. Colour dirty white, often slightly tinted yellow from the investing membrane, and from thin layers of punctured membrane alternating with the laminæ of shell. The parietes, in old specimens, have very irregular longitudinal ridges, or rather plates projecting out, sometimes much branched, and generally curved inwards so as to meet each other, thus forming round the basal margin a circle of cylindrical apertures. In old large specimens the radii are not developed, and till the compartments are disarticulated there is no trace of the toothed structure of their sutural edges: in this condition the sutures exist as deep, rugged, narrow fissures. In younger shells, the radii, though narrow, are distinct, and have their surfaces transversely ribbed, and their edges toothed and interlocked with the teeth of the recipient furrow. Some of the specimens present a curiously deceptive resemblance to [Elminius plicatus]. Basal diameter of largest specimen, one inch and a quarter; height one inch.
The parietes are remarkably thick, but the compartments separate easily: I have, however, seen one instance in which they were partially calcified together. Their internal surfaces are very smooth. The sheath does not descend low. The alæ project rectangularly; they have thick edges, and these are coarsely crenated in transverse lines. Of the radii sufficient has been said.
Scuta (fig. [2 b]): these, in all the specimens seen by me but one, have been deeply corroded, and their outline, as in [Chthamalus], considerably modified: in the one specimen well preserved, the exterior growth-ridges were extremely prominent. The articular ridge does not project much, nor is the articular furrow very deep. There are more or less distinct crests for the lateral depressor muscles. The Terga are rather narrow, with a small rounded spur, moderately distinct. The tips of the crests for the depressor muscle barely depend beneath the basal margin.
Mouth: labrum considerably bullate, with the crest hairy and furnished with a few most minute teeth. Palpi small, with their tips not nearly touching each other. Mandibles with four teeth, of which the lower ones are laterally double: inferior pectinated portion small. The maxillæ are notched, but their outline differed on opposite sides of the individual examined. Outer maxillæ bilobed on their inner face.
Cirri.—The first pair has the rami unequal in length by about three segments, having six segments on one and nine on the other ramus. In the second pair the anterior ramus is remarkably short and extremely broad; the five segments of which it is composed being thickly covered with bristles, some of which are very coarsely and doubly pectinated: the posterior ramus is nearly twice as long as the anterior ramus, and has eleven segments; of these, excepting the two basal segments which are rather thickly covered with spines, the others resemble in the arrangement of their spines the four posterior pairs of cirri, with the exception that there is a single transverse row of rather long spines along the upper and inner lateral edge of each segment. The segments in all the four posterior pairs of cirri resemble each other in bearing each four pairs of main spines (of which the two lower pairs are short), with a tuft of small intermediate spines.
The penis is remarkable from its very small size and shortness, not being more than once and a half as long as the pedicel of the sixth cirrus.