480 THE VOYAGE OF H.M.S. CHALLENGER. 



fibres ; and the interspaces include two or three large spiracula. All the spinelets are 

 uniformly protuberant, and that only to a slight degree ; they are rather closely placed, 

 and the whole abactinal area is thickly covered with rather fleshy wrinkled skin, presenting 

 a somewhat spongy and subpapillose appearance, and a slightly scabrous feeling to the 

 touch. The primary meshes are not very distinctly marked out superficially, and the 

 hexagons consequently appear to overlap or run into one another in many cases. The 

 oscular orifice is small and inconspicuous. 



The ambulacral furrows are broad and more or less petaloid, the closely placed and 

 prominent transverse adambulacral spine-combs adding greatly to the appearance of 

 breadth. The tube-feet are arranged in quadruple series. The combs of spines forming 

 the adambulacral armature are broad, a feature further enhanced by their method of 

 arrangement. Each alternate comb has usually two spines less ; in this way combs of 

 seven to eight spinelets alternate regularly with combs of five. The larger combs radiate 

 well over the furrows, whilst the smaller ones, on the other hand, are considerably retired 

 from the margin, the innermost spine standing perpendicularly, or even directed slightly 

 outward. Hence when seen from above, the smaller combs appear to occupy little more 

 than one-half, or at most two-thirds, the space of the larger combs. In the larger combs 

 the innermost spine is smaller and shorter than the rest, frequently not more than half 

 the length. In the smaller combs the innermost spine is much smaller still, often quite 

 aborted and apparently absent. The other spines are nearly equal in length, and both 

 combs are uniform with one another in this respect. The combs are thickly webbed, and 

 have large and elongate saccular extensions developed over the extremities of the spinelets. 



The mouth-armature resembles that of Retaster verrucosus. The mouth-spines are 

 eight to ten in number, four or five on each plate, both series being webbed together, 

 and forming a narrow scoop-like fan. The secondary or superficial mouth-spines, one on 

 each plate, are thin, cylindrical, not tapering, no longer than the mouth-spines, and 

 covered with membrane. 



The actino-lateral spines are of moderate length, reaching up to the margin of the 

 test ; they are hidden in membrane, of which a saccular but not indented prolongation 

 extends beyond the extremities as a fleshy marginal fringe. The segmental apertures of 

 the abactinal chamber are very large and elongate, situated well within the transverse 

 combs, and quite hidden thereby. 



Colour in alcohol, purplish grey. 



Locality. — Station 149h. Off Cumberland Bay, Kerguelen Island. January 29, 

 1874. Lat. 48° 45' 0" S., long. 69° 14' 0" E. Depth 127 fathoms. Volcanic mud. 

 Surface temperature 39°'8 Fahr. 



Remarks. — Retaster peregrinator resembles in general form Retaster verrucosus from 

 the Atlantic side of the Strait of Magellan, of which it may be regarded as the representa- 

 tive in the Southern Ocean area. The two forms are, however, specifically distinct, and 



