302 
THE VOYAGE OF H.M.S. CHALLENGER. 
3. Oxea, long, slender, fusiform ; occurring very sparingly, chiefly near the walls of 
the larger canals, to which they run parallel ; the inner end of the spicule is sharply 
pointed, the outer has not been observed; more than 0’71 mm. in length by 0’004 
mm. in thickness. 
II. Microsclere. 4. Spirasters, these are mostly of the typical spiral form, but they 
vary almost indefinitely ; the spire varies in form and dimensions, and the spines vary 
in both these characters and in number ; sometimes the spines become much reduced 
in number, enlarged and produced into secondary spines, sometimes with an increase 
in size and reduction in number of the spines, the spire becomes thickened into a stout 
fusiform body, and variation in this direction may proceed so far that at length a minute 
fusiform centrotylote oxea, such as is represented by an accidentally unnumbered figure 
placed immediately above fig. 18, PI. XXXIV., may be produced. The commonest form 
of spiraster is about 0‘02 to 0*024 mm. long, with spines 0*005 mm. in length. 
Throughout a great part of the ectosome a number of problematical hollow rods 
occur, thickly distributed, lying with their long axes variously orientated, but parallel 
to the surface ; they consist of a thin siliceous shell, cylindrical in form, with rounded 
closed ends, hollow, and apparently empty within ; 0*071 mm. long by 0*0065 mm. in 
diameter. As they are not present in all parts of the ectosome, and as they are quite 
unlike any known form of cylindrical sponge spicule, they can hardly be regarded as 
spicular components of the sponge ; they may possibly be Diatoms like those met with 
in Anthastra pyriformis (p. 148). 
Colour. — Y ellowish-white. 
Habitat. — ^Station 122, off Pernambuco, September 10, 1873; lat. 9° 5 ' S., long. 
34° 50' W.; depth, 350 fathoms ; bottom, red mud. 
Florida, 152 to 228 fathoms, and 7^ fathoms (0. Schmidt). 
Remarks . — So far as one can judge from Schmidt’s very imperfect description, the 
single specimen above described belongs to the species Corallistes typus, 0. Schmidt. 
Schmidt’s specimens werp obtained from Florida at a depth of 152 to 228 fathoms, 
though one fragment was labelled 7 ^ fathoms, as Schmidt thinks by mistake. That 
which he figures closely resembles our sponge both in form and size ; but certain irre- 
gularly bent uniaxial spicules which are represented as distributed through it are certainly 
not present in ours. These spicules, however, have probably been introduced, as Carter ^ 
affirms, by some parasitic sponge. 
The Challenger specimen is 29 mm. in height, 35 mm. in width, and 13 mm. in 
thickness. The oscules, which are from 0*5 to 1*0 mm. in diameter, lead into excurrent 
canals, which immediately branch into the substance of the sponge ; the pores lead into 
incurrent canals, which descend perpendicularly through the ectosome and open into longi- 
^ Carter, Ann. and Mag. Nat. Hist, ser. 4, vol. xii. p. 443, 1873. 
