86 



peristome. Stolon not continuous with the proximal end of the zooecium, very slender, bifurcating 

 at intervals, the branches usually given off in the interspaces between the zooecia; with a few 

 transverse diaphragms. Polypide with a gizzard. Collar apparently absent. Tentacles 8. 



In its general appearance the present form has a close resemblance to the British species 

 figured by Aeder and Hincks. The latter author has, however, described an "aperture", or 

 flat membranous region on the side of the peristome facing the stolon. Alder has, moreover, 

 described a well developed collar. As I have been unable to find certain evidence of Hincks' 

 aperture and of Alder's collar, I ara not certain that the reference of the 'Siboga' specimens 

 to the British species is correct. The species is, however, represented by so small an amount of 

 material (307. B., one colony; 451. C, two or three zooecia) that I hesitate to describe it as 

 distinct. It is possible that I have overlooked the parts in question; or that the specimens observed 

 are to be regarded as a variety in which they are really absent. In view of its minute size it is 

 not impossible that some of the features ordinarily present are not here developed. Hincks leaves 

 the existence of a gizzard doubtful; but I have no doubt of its presence in the 'Siboga' material. 



It is not easy to be positive with regard to the mode of attachment of the zooecium 

 to the stolon. At first sight it might be supposed that a narrow, pointed, proximal end of the 

 zooecium was connected with the stolon. But a more careful examination seems to show that 

 the pointed end (fig. 16) is merely one of the spines developed from the margin of the zooecium, 

 the real attachment of which is somewhere near the middle of the adnate portion. This region 

 is flattened and is provided with a few spinous processes on one side only, instead of on 

 both sides, as in British specimens. The stolon generally runs along the attached part of the 

 zooecium, in close contact with it, on the side opposite to that which bears the spines. The 

 diaphragms of the stolon do not seem to be constant in position. 



In one case (fig. 17) the tentacles are protruded, and eight can be counted. In the same 

 zooecium there is a small emargination on one side of the zooecium, close to the base of the 

 kamptoderm. This may represent the "aperture"; but I have not been able to find it in other 

 zooecia. The peristome is usually marked by a number of fine circular striae, and the orifice 

 is more or less square. 



The zooecium shown in fig. 15 is 290 u. long, and 140 u in greatest breadth. The 

 longest zooecium in fig. 14 is 360 u. long. 



Buskia australis Jullien J ) seems to be an allied species; but it has a well developed 

 aperture. No figure is given in the original account. B. socialis Hincks 3 ) is another form allied 

 to B. nitens^ from which it is said to differ in its much larger size, as well as by its erect 

 habit and by other characters. 



It might be suggested that this species should be referred to Arachuidiitm, but its mode 

 of branching seems to exclude this possibility. The cruciform arrangement is not found here, 

 and the branches of the stolon do not correspond with the bases of the zooecia. It has, however, 

 some resemblance to Arachnidium simplex, described by Hincks from Barents Sea 3 ). 



1) JUI.I.IEN, J., 1888, p. 22. 



2) Hini KS, T., 1887, "Pol. Adriatic", Ann. Mag. Nat. Hist. (5) XIX, p. 310, PI. IX, figs 7-7/'. 



3) Ibid., 1SS0, "Hydr. Pol. Barents Sea", Ann. Mag. Xat. Hist., (5) VI, p. 2S4. PI. XV, figs io. II. 



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