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Show 1869.] DR. J. D. MACDONALD ON A NEW CIRRIPED. 441 Moreton Bay*, I found them beset with beautiful little pink-tinted barnacles, having a vitreous-looking capitulum, about one-eighth of an inch in length, with shelly depositions bearing an important relation to the rudimentary valves of Dichelaspis and Conchoderma. In general form, however, and even in many details of their anatomy, these little parasites are perfect miniatures of Lepas anatifera, their most striking character being that the valves, which are semitransparent in the greater part of their extent, are distinctly in articulation with each other, or closely approximate (see Plate XXXIII. fig. 3). The peduncle is of considerable length, and cylindrical, though tapering a little towards the capitulum (Plate XXXIII. figs. 1 and 2). It is, moreover, so transparent as to exhibit, under a low power, its outer circular and inner longitudinal layer of muscular fibres, with the contained tubular structure and pink-coloured ova. When more matured these latter reach the back part of the cavity enclosed by the valves, where they become arranged in a single leaf-like layer, which, adapting itself to the curvature of the posterior and lateral valves, receives the body of the animal in its concavity. In this single expansion the union of two ovigerous lamellse is indicated by a central notch in its inferior border (fig. 2, b & c). To an ordinary observer the oral organs would present a great similarity to those of Lepas, but they appear to be somewhat more prolonged, so as to form a kind of proboscis. In the capitulum the valves are five, approximate, corneous, and strengthened by the deposit of shelly matter, as above mentioned; besides which they are marked with distinct lines or increments of growth, and dotted with minute points, indicating at least a pseudo-cell- structure (Plate XXXIII. fig. 3). These lines of growth are obtusely angular in the scuta (b), but rather semicircular in the terga (c) and carina (d). The centre of development is posterior and basal in the carina, anterior and basal in the scuta, and posterior and subapical in the terga. The shelly supporting piece of the scuta consists of a long and fusiform occludent segment, connected with a rudimentary basal one, and an intervening oblique ray directed towards the middle of the carina. The shelly part of the terga is subapical and narrowly crescentic, with the convexity near the dorsal border. Finally, the shelly framework of the carina consists of a narrow mid-rib extending only to the base of the terga posteriorly, but bifurcated at the proximal end, where each limb skirts the base of its own moiety. In the occludent margin of the capitulum the lines of growth (Plate X X X I V . b) increase in length and thickness from before backwards. The parts of the mouth more particularly considered afford the following characters:- The labrum (Plate X X X I V . c) is protuberant or bullate, its angular edge supporting a row of fine conical tubercles. * This species is also abundant at Sydney, and amongst the islands of the South-western Pacific. |