Thircl pair (PI. XXIV, fig. 2), branches somewhat unequal, of 10 and 11 segments. 

 Hairs do not form such dense tufts as on 2 nd cirrus. Small but strong teeth along the anterior 

 face of all the segments of the longer ramus. The teeth are arranged in groups of 2 to 4 on 

 the distal half of the segments near the anterior margin, and in several rows. One of the 

 spines situated on the tij) of the last segment of this ramus is much stronger and looks 

 almost like a claw. 



Fourth pair has 1 9 and 20 segments respectively in the two branches. The 5 or 6 lower 

 segments of the slightly shorter branch (with 1 7 to 19 segments) bear small teeth, either single, 

 or doublé, or in groups of 3 or 4 near the anterior face (PI. XXIV, fig. 3). These teeth are 

 not situated exactly on the margin of the segments, but at a short distance from it, on the 

 surface of the segments. 



Fifth pair has 18 and 19, sixth 19 and 20 segments. Middle segments about twice 

 as long as broad. Greatest number of pairs of spines on inner face 4 pairs. One of the hairs 

 of the small group seen on exterior face of the segments, near the extremity, very long. 



Penis: long, tapering towards extremity, hardly any hairs on surface. 



The specimen of this species belonging to the collection of the Siboga, was found 

 attached to a very long threaddike organism (a Gorgonacean) with distinct swellings at regular 

 intervals. This seems to be Scirpcarella gracilis. The substance covering the stem of the Gorgo- 

 nacean is continued — as I pointed out above — over the surface of the Balanits\ only after 

 taking it away, I found that the said stem was quite enclosed in a longitudinal furrow of the 

 slightly cup-formed basis. 



The animal was dredged at : 



Stat. 204. September 20, 1899. Lat. 4°2o'S., Long. I22°58'E. The Station lies between the 

 islands ofWowoni and Buton, northern entrance of Buton-strait. Depth 75 — 94111. 

 Bottom: sand, with dead shells. 



8. Sectio: Bathy-Balanus 



26. Balanus pentacrini n. sp. PI. XXIV, fig. 4 — 10. 



Shell white, surface of valves more or less distinctly furrowed longitudinally. Orifice 

 large, toothed. Radii broad, summits oblique, alae with rounded summits. Scutum distinctly 

 furrowed horizontally, articular ridge prominent, no adductor ridge. Tergum with the surface 

 somewhat undulating and the spur situated near the basi-scutal angle. Parietes, radii and basis 

 without pores. Labrum without notch. 



This interesting deep-sea species connects the true Balani with the forms without radii, for 

 which I propose to create the new genus Hexclasma. In the present species the outer surface of the 

 shell is white and smooth ; in the older (larger) specimens it is distinctly furrowed longitudinally 

 (especially so towards the basal margin), in the smaller ones, however, either not or only 

 indistinctly so. It is, moreover, feebly striated horizontally. The radii are rather broad and have 

 the summits oblique, they are distinctly striated horizontally; the alae are also broad and have 

 the summits rounded. The orifice is toothed. The whole shell (PI. XXIV, lig. 4), especially 



