REPORT ON THE TETRACTINELLIDA. 
9 
TetUla coronida,^ n. sp. (PL XXXVIIL figs. 13-17). 
Sponge (PI. XXXVIIL figs. 13, 14) spherical, depressed (button-shaped), with a some- 
what sharply marked equatorial margin ; surface slightly hispid, raised into low conules, 
incrusted with grains of sand, Foraminifera, and other foreign bodies, base produced into 
rooting fibres. A single oscule situated in the centre of the upper surface, its margins 
produced into a short membranous transparent tube. 
Spicules. — I. Megascleres. 1. Oxea, isoactinate, fusiform, very sharply pointed, 3 '37 
by 0’037 mm. 
2. Protrisene (PI. XXXVIIL fig. 15), rhabdome regularly tapering from the cladome 
to a filiform extremity, 3*37 by 0‘02 mm.; cladi usually strongylate 01 mm. long, 
chord 0‘071 mm. 
3. Anatrisene (PL XXXVIIL fig. 16), rhabdome fusiform, 714 mm. long, at the 
actinal origin about 0'015 mm. in diameter, tapering thence in both directions, esactine 
ending in a filiform extremity, ecactine enlarging below the cladal centre to twice its 
previous diameter at its origin; cladi 01 mm. long, chord Oil mm. 
4. Anamonsene (PL XXXVIIL fig. 17), this is a reduced and modified protrisene, 
two of the cladi being suppressed, and the remaining one recurved at about the middle of 
its length; the single cladus is 0’28 mm. -long, measured along two chords, one from its 
origin to the middle of its curvature, the other thence to its termination. 
II. Microsclere. 5. Sigmaspire of the usual form, 0'016 by 0'002 mm. 
Colour. — Dark grey, speckled with black and white by incrusting foreign matter. 
Habitat. — Station 150, off Heard Island, February 2, 1874; lat. 52° 4' S., long. 
71° 22' E.; depth, 150 fathoms; bottom, coarse gravel; bottom temperature, 35°‘2. 
Remarks. — This little sponge, represented about twice its natural size in the illustra- 
tion (PL XXXVIIL figs. 13, 14), measures 13 mm. in length by 10 mm. in width and 8 
in height. It resembles Tetilla pedifera in so far as it is characterised by the remarkable 
shepherd’s crook spicule or reduced protrisene, which, however, is far less abundant in 
this sponge than in Tetilla pedifera. 
The two species are otherwise very sharply distinguished ; they not only differ in 
habit, external form, and in the characters of the oscules, but in Tetilla coronida some- 
what large sigmaspires are abundantly present, while microscleres do not occur at all 
in Tetilla pedifera. The single cladus of the anamonsene in the latter sponge is only 
one-half the length of that in the former. 
Although the anamonsene looks at first sight like a reduced anatrisene, it is much 
more probably a modified protrisene ; the single cladus for the first half of its course pro- 
jects forwards, and the suppressed cladi, as represented by short axial fibres which 
^ ( 3of, crook-beaked. 
(ZOOL. CHALL. EXP.— PART LXIII. — 1887.) 
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