“Guitarra fimbriata, n. gen. et sp. P1. XIII. figs. 2-5, and
Pl. XV. fig. 34.
General form conical (figs. 2 & 3); surface villous, even; villi formed by the projecting ends of the skeleton-spicules, arranged in tufts close together (fig. 3, d), and somewhat spirally over the body, lengthened into a tubular fringe around the apex (fig. 3, a). Sessile. Colour grey. Vent chiefly apical (fig. 3, a), where it is surrounded by the fringe of long spicules just mentioned, while smaller vents (fig. 3, c) are scattered over the surface generally. Pores not seen. Internal structure massive, permeated by the excretory system of canals, which has its chief vent at the apex; charged with skeleton- and flesh-spicules, and surrounded by a cortical layer chiefly composed of the former, whose projecting ends give the villous surface (fig. 3, d).
Spicules of two kinds, viz. skeleton- and flesh-spicules. Form of skeleton-spicule, of which there is only one, smooth, acerate, fusiform, finely pointed, and nearly straight; average largest size 27 by 1/2-1800th of an inch in its greatest diameters (P1. XV. fig. 34), that of the fringe round the apex much longer, viz. 1-24th inch. Flesh-spicule equianchorate, in which the lateral arms are so blended with the shaft as to convert the whole into a flattened plate, of an hourglass- or guitar-shape, constricted in the centre and round at the ends (Pl. XIII. fig. 4, a b c), bordered inside throughout by a fringe directed inwards towards the shaft (fig. 4, d), leaving a trapezoidal, clear area opposite the constriction, and a narrow, obovate one at each end (fig. 4, b c): anterior arm at each end flat, expanded into a circular or obtuse, thin, elliptical plate, presenting the same kind of fringe round its margin, directed inwards, and leaving, as in the shaft, a transparent ovate area in the centre (fig.4, b); anterior arm equal in width to the end of the shaft &c., to which it is parallel transversely, but longitudinally inclined from it at an acute angle beginning at the end (fig. 4, a), where it is united to the shaft by a short falx (fig. 4,f), opposite to which is a large, clear, circular tubercle (fig. 4, e): average length of largest form 16-6000ths inch; widest part 6-6000ths; constricted part 3-6000ths. Size of entire specimen about 6 by 4-12ths of an inch in its largest diameters. Fringe of spicules round the apex 1-24th inch broad.
Hab. Deep sea.
Loc. Atlantic Ocean, off the N.W. coasts of the British Isles.
Obs. The jar containing this, with a specimen of Podospongia Lovenii, Bocage, one of Desmacella pumilio, Schmidt, and a fragment of an Hexactinellid sponge (Askonema?) bears no label. It is remarkable for the form of the anchorate spicule, which, but for reference to that of Halichondria incrustans, above given, is so modified in form that it could hardly be otherwise understood. Although the average largest size of this spicule is figured, it is present of all intermediate sizes down to an embryonic form not more than 2-5000ths inch long, in which the outlines alone of the hourglass-shape can be distinguished (fig. 5). Further, it is remarkable for having only one form of skeleton-spicule, and that acerate, and only one form of flesh-spicule, which, so far as is known, is unique; also for the length of the skeleton-spicules at the apex of the body, where they present a tubular fringe round an apical vent, like that seen in some of the Calcispongiæ, ex. gr. Grantia ciliates &c. I think, from the villous even surface and general composition of this sponge, it might be necessary to place it among the Suberites, in which case it would come into my 5th division, viz. RAYNERIÆ.”
(Carter, 1874)
