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



a locality lialfway between Kerguelcn Island and the Cape of Good Hope — the one 

 (PI. XVI. fig. 9) (Station 146, lat. 46° 46' S., long. 45° 31' E.) from a depth of 1375 

 fathoms and a bottom of Globigerina ooze; the other (PI. XVI. fig. 1) (Station 147, 

 lat. 46° 16' S., long. 48° 27' E.) from a depth of 1600 fathoms, and a bottom of Diatom 

 ooze. Although none of these specimens is wholly uninjm-ed, the combination of all 

 the three affords a clear conception of the form and structure of the species. The foi-m 

 can be most clearly recognised from what is really the most macerated specimen, but 

 which is preserved in its entire length (PL XVI. fig. 9). This consists of a conical tube, 

 narrowed downwards and running out inferiorly into a basal tuft ; while the upper 

 transversely truncated extremity is bounded by a narrow marginal ridge and closed by a 

 sieve-plate which extends within the latter, and is arched slightly outwards in its 

 central portion. The specimen obtained at Station 160 (PI. XV. fig. 1) represents only 

 the much injured lower end with the basal tuft, while of the decidedly larger specimen 

 from' Station 147 (PL XVI. fig. 1) only the upper portion with the sieve-plate and the 

 relatively well-preserved soft parts persist. 



The whole outer surface of the sponge exhibits the fine small points which occurred on 

 Holasciis stellatus. Here also on the inner side of the tube there extends a system of 

 intersecting longitudinal and transverse ledges which form quadrate meshes with central 

 pits (PL XVI. fig. 1). The framework of the terminal sieve-plate, though not quite 

 regularly constructed, exhibits approximately radial and circular strands of beams, from 

 the intersections and nodes of which small prickles project outwards (PL XVI. figs. 9, 10). 



The principal framework of the wall of the tube lies towards the inner surface, and 

 consists of strong smooth tetracts. The somewhat long longitudinal rays cross the shorter 

 transversals externally. Numerous comitalia with a variable number of long narrow rays 

 are attached both to the longitudinal and transverse rays of the principalia (PL XV. 

 fig. 2 ; PL XVI. fig. 2). 



On a transverse section of the somewhat thick wall of the tube (of the fragments 

 figured in PL XVI. fig. 1) a system of rough hexacts is observed, \\dth rays disposed in 

 radial, longitudinal, and transverse directions, and apposed to one another to form a 

 framework of beams enclosing cubical meshes (PL XVI. fig. 2). The outermost and 

 innermost of these hexacts correspond in position and direction with the hexact 

 hypodermalia and pentact hypogastralia, to the long parenchymal ray of which they are 

 symmetrically joined. The other ii-regularly scattered parenchjnnalia consist of isolated 

 graphiohexasters with bundles of long, very delicate, parallel terminal rays, and of those 

 characteristic fibulae, which I am inclined to derive from greatly reduced oxyhexasters 

 with bent terminal rays. One can frequently observe at some distance from the central 

 nodes and upon each of the two rays a boundary line, at which the straight central, 

 thicker segment passes into the thinner terminal portion (PL XV. fig. 3c, d). I regard this 

 straight, inner, thicker portion as corresponding to the principal ray, the bent outer 



