184 
THE VOYAGE OF H.M.S. CHALLENGEE. 
Spicules. — I. Megascleres. 1. Oxea, 1’46 mm. in length. 2. Dichotrisene, rhab- 
dome 1'46 mm. in length, protocladi 0'08 mm., deuterocladi O’lOS mm. in length, 
chord 0 35 mm. 3. Anatrisene, rhabdome 0‘008 mm. in diameter, cladi 0 039 mm., 
chord 0'0645 mm., sagitta 0'021 mm. in length. 
II. Microscleres. -4. Anthaster, actines variable in number, usually five to seven, 
O'OIG mm. in length. 5. Chiaster, actines slender, hair-like, not tylote, total diameter, 
0'02 mm. 
Colour. — Whitish-grey. Size, 13 mm. in diameter. 
Habitat. — Port Phillip Heads, South Australia. 
Remarhs. — Mr. Carter had the kindness to send me part of a spirit-specimen of this 
sponge, and I am thus able to assign it to the genus Antliastra with certainty. 
Stelletta boglicii, 0. Schmidt. 
Stelletta hoglieii, 0. Schmidt, Spoug. Adriat. Meeres, p. 47, p]. iv. fig. 4, 1862. 
Sponge spherical ; surface hispid, covered with attached foreign bodies ; cortex 
about 244 mm. in thickness. 
Spicules. — I. Megascleres. 1. Oxea, from 2‘78 by 0‘07 to 3'08 by O OG mm. 2. 
Plagiotrisene, rhabdome 1‘8 by 0'07 mm., cladi from 0'07 to 0427 mm. in length. This 
spicule is frequently reduced to a disene or monsene. 
II. Microscleres. 3. Ectosomal chiaster, actines slender, baciUary, terminally 
truncate, 0'012 mm. in diameter. 4. Choanosomal oxy aster, actines numerous, conical, 
passing into a small centrum, a single actine from 0'013 to 0'023G mm. long. 
Colour. — Brown externally, white within. 
Habitat. — Lesina, at considerable depths in the Adriatic Sea. 
Remarhs. — The plagiotrisenes are reduced through all stages down to an oxea ; one 
cladus may be present, and the axial fibres of two others, or the axial fibres may also be 
absent ; the single cladus may arise as an evident branch from the rhabdome, or may 
form merely the bent termination of an oxea. 
Stelletta coactura (Bwk.). 
Ecionema coactura, Bowerbank, Mon. Brit. Spong., vol. iii. p. 269, pL Ixxxii. figs. 13-19, 1874. 
Sponge massive, free ; surface even, hispid, covered vdth numerous small pebbles and 
other attached foreign bodies ; oscules inconspicuous ; pores in sieves, large ; cortex nearly 
2 mm. in thickness. 
Spicules. — I. Megascleres. 1. Oxea, fusiform, tornote, 1'91 by 0'04 mm. 
