EEPORT ON THE TETEACTINELLIDA. 
140 
face shown in PL XV. fig. 2. One remarkable fact in connection with them is the 
presence of well-developed protrisenes throughout their whole course from the origin to 
the surface. The dichotrisenes, evidently modifications of the protrisenes, and the ana- 
trisenes, occur only near the surface, beyond which they do not project except in the 
sheltered depression shown in the upper edge of fig. 1. Here the anatrisenes extend 
outwards for about 0'25 mm., and some of them, together with fully-developed oxeas, 
occur amidst some attached foreign material, free and completely extruded from the 
sponge. 
The anatrisenes are sometimes reduced to anadisenes and anamonsenes, the latter some- 
what resembling the anamonsenes of Tetilla pedifera, except that the cladus is far 
shorter in length. 
Anthrastra ridleyi, Sollas. 
Edonema ridleyi, Sollas, Prelim. Account, Sci. Proc. Roy. Dubl. Soc., vol. v. p. 191, 1886. 
Sponge ovate ; a few papillary processes (apparently for attachment) at the lower end; 
several small oscules on the summit. 
Spicules. — I. Megascleres. 1. Oxea, massive, fusiform, straight or curved, sharply 
pointed or not; 4’07 by O’llS mm. 
2. Orthotrisene ; rhabdome conical, massive, sharply pointed or rounded off near the 
end ; cladi stout, conical, diverging outwards and slightly forwards. Rhabdome 4'0 by 
0 118 mm., cladi 0'27 to 0‘32 mm. long, chord 0'58 mm. 
3. Anatrisene; rhabdome slender, conical, sharply pointed ; cladi diverging more out- 
wards than backwards; front of the cladome rounded. Rhabdome 3'6 by 0‘03 mm., 
cladi 0‘103 mm. long, chord 0’183 mm., sagitta 0'08 mm. 
II. Microscleres. 4, Anthaster, smal], actines usually numerous, a single actine of a 
tetrad form from O'Ol by 0'0039 mm. 
5. Chiaster, actines slender, hair-like, tylote, no visible centrum ; O'Ol 58 mm. in 
diameter. 
Colour. — Yellowish- white. 
Habitat . — Port Jackson, June 3, 1873; depth, 30 to 35 fathoms. 
Remarks. — The single specimen obtained of this sponge is a prolate ellipsoid, with a 
minor axis of 15 mm. and a major axis of 23 mm. It differs from Ecionema pyriformis 
in possessing orthotrisenes instead of dichotrisenes, and in the reduction of the anthaster, 
which differs only slightly from a chiaster. Both sponges bear a general resemblance 
to Antliastra {Stelletta) tethyopsis, Carter ; which, however, is distinguished by much 
larger megascleres, the oxea measuring 8'68 by 0'05 mm., and the dichotrieene 8'68 by 
0'07 mm. 
