REPORT ON THE TETRACTINELLIDA. 
431 
Habitat. — Station 208, off Manila, January 17, 1875; lat. 11° 37' N., long. 
123° 31' E. ; depth, 18 fathoms; bottom, blue mud. Trawled. 
Remarks. — There are two specimens of this sponge, one nearly 20 mm. in diameter, 
and the other 13 mm. The larger specimen (PL XLIV. fig. 7) is gemmiferous. 
Tethya ingalli, Bowerbank (PL XLIV. figs. 15, 16). 
Tethea ingalli, Bowerbank, Proc. Zool. Soc. Bond., p. 119, pi. v. figs. 11-17, 1872. 
„ diftoni, Bowerbank, op. dt., p. 16, pi. iii. figs. 14-18, 1873. 
„ robnsta, Bowerbank, op. dt., p. 10, pi. ii. figs. 12-17, 1873. 
Tethya diftoni, Ridley, “Alert,” p. 624, 1885. 
? ,, „ Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. xvii. p. 122, 1886. 
Sponge (PL XLIV. fig. 15). — More or less spherical, attached, surface smooth, 
without conules, but raised into low rounded bosses. Cortex (PL XLIV. fig. 16) thick, 
not differentiated into an outer and inner layer, fibrous throughout. Pores simple, singly 
distributed, chiefly over the depressions between the mammillation of the surface, leading 
each into a long narrow canal of uniform diameter, which completely traverses the cortex. 
Intercortical cavities absent. Oscules similar to the pores, but sometimes larger, not 
exceeding 0'5 mm. in diameter. 
Spicules. — I. Megascleres. 1. Strongyloxea, as in the genus, 1'6 to 17 mm. in 
length by 0'026 to 0’032 mm. in diameter. 
II. Microscleres. 2. Cortical spheraster, as in the genus, from 0*065 to 0*085 mm. 
in diameter. 
3. Somal chiaster, as in Tethya seychellensis, E. P. W., from 0*0118 to 0*0157 mm. in 
diameter. 
4. Choanosomal oxyaster, centrum absent, actines slender, straight or curved, usually 
few in number, frequently six, arranged along three rectangular axes ; erectly spined ; 
rarely dichotomising ; spines few, varying in number and length, irregularly distri- 
buted ; total diameter of the spicule, 0*035 to 0*043 mm. 
Colour. — Orange-red when living, pinkish-grey in spirits. 
Habitat. — Station 162, off East Moncoeur Island, April 2, 1874 ; lat. 39° 10' 30" S.; 
long. 146° 37' 0" E.; depth, 38 fathoms ; bottom, sand and shells. Dredged. 
Port Jackson ; depth, 6 to 15 fathoms. 
Distribution. — Fremantle, Australia [Tethea ingalli, Bowerbank, &c. ; Tethea diftoni, 
Bowerbank, loc. cit.)-, Australia [Tethea rohusta, Bowerbank, loc. cit.); Port Phillip 
Heads, Australia [Donatia [Tethea) diftoni, Bowerbank, Carter, Ann. and Mag. Nat. Hist., 
ser. 5, vol. xviii. p. 463, 1886); Seychelles, depth, 12 fathoms (Ridley, loc. cit.). 
Remarks. — I have examined types of Tethya diftoni and Tethya ingalli, and find 
no specific difference between them. The character on which Bowerbank relied for their 
