§9 



3. Buskia pilosa n. sp. (PI. V, figs 11 — 13). 



Type. 501. E. Stat. 163. Near Seget, W. entrance Selee (Galewo) Strait, 29Metres; sand and stone, 

 mixed with mud (on rootlets of Caberea lata). 

 Also from Torres Straits (Mus. Zool., Cambridge), A. C. Haddon Coll., Reg. Feb. 24, 1898 

 (on a Hydroid). 



Zooecia very large, more or less plano-convex in shape, attached by a flattenecl base, 

 which is generally at least two thirds of the entire length of the zooecium. The basal wall is 

 thin and membranous, and is continued along one surface of the free portion as far as the 

 orifice. Frontal and lateral surfaces very convex, covered with a thick cuticle, all parts of which 

 give off a profusion of spines, which are of several kinds. Stolon slender, very irregular and 

 frequently geniculate; dilating at intervals into slight expansions, from which branches are given 

 off, as in B. setigera. 



The zooecia are all dead and empty ; and there is thus no certain proof that the organism 

 here described is a Polyzoon. But I think there can be no doubt of this-, and the species has 

 sufficiënt resemblance to B. setigera to justify its reference to the same genus. The cuticle of 

 the free surface is very thick and stout; since in the Torres Straits specimen, which is a dry 

 mount, the zooecia show no noticeable shrinkage, and agree precisely in form with the 'Siboga' 

 specimens mounted in glycerine or Canada balsam. The continuation of the flat, membranous 

 base as far as the orifice indicates that an aperture is represented, as in typical species of 

 Buskia. The spines are a specially characteristic feature of this form, and the following kinds 

 may be distinguished : — (a) those of the greater part of the free surface, which are relatively 

 short, pointed and curved ; (ó) a tuft of much longer spines, which appear to correspond with 

 the oral spines of B. setigera : they are, however, much more numerous than in that species 

 and are not jointed; while they usually have a sinuous outline; (e) those of the edge of the 

 convex portion of the zooecium, which are commonly bifurcate and are used for attachment to 

 the object on which the colony is growing. 



The distal region of the zooecium is free, and forms a short "peristome", the orifice 

 being no doubt terminal and surrounded by the oral spines ; though the orifice cannot actually 

 be demonstrated except so far as it is indicated in fig. 13. Xone of the details of the internal 

 anatomy can be made out ; as the zooecia are quite empty, with the exception of one or two 

 which contain a multinucleated mass which looks like an encysted (intrusive) Protozoon. 



The stolon has a close resemblance to that of B. setigera ; the swellings from which 

 branches are given off being much like those of that species. But the stolon of the present 

 species is very irregular in outline and is frequently angulated. It is of considerably smaller 

 diameter than the Gz^r^tf -rootlets (fig. ii,r) over which it creeps. 



The zooecium shown in fig. 13 measures 600;/ in length without its spines: and is 

 260 u. in greatest diameter, without the spines. The finer stolon-threads are 10 [i in diameter, 

 while the width of the Caócrea-rootlets is about 50 ft. 



S 9 



SIBOGA-EXPED1T1E XXVIII». 



