202 
THE VOYAGE OF H.M.S. CHALLENGEE. 
word Stellettinopsis is an odious combination of Greek and bad Latin, and hybrid names 
such as this are expressly condemned by the Stricklandian rules. I therefore propose a 
fresh definition and a new name for the type, and a fresh type and a new name for 
the definition. 
Genus (?). 
Stelletta pathologica, 0. Schmidt. 
Stelletta pathologica, O. Schmidt, Spong. Kiiste v. Algier, p. 19, pi. iiL figs. 3, 4, 1868. 
Sponge. — Irregular knoll-like masses with a rough surface, cortex 0*5 mm. in thick- 
ness, not differentiated into two layers, apparently collenchymatous. 
Spicules. — I. Megascleres. 1. Oxea, long, slender, very attenuately pointed, col- 
lected in loose fibre-like bundles, which are directed at right angles to the cortex, 2 "3 8 
by 0’012 mm. 2. Mesotrisenes {vide pi. iii. fig. Set, loc. cit.), rhabdal aetines conical, 
oxeate, 0*875 mm. by 0*0434 mm., cladi conical, oxeate, variously inclined to the axis of the 
rhabdome, subject to numerous irregularities in form, number, and position, frequently 
reduced to two or one in number, and about 0*238 mm. in length. 
II. Microscleres. 3. Oxyaster, aetines conical, oxeate, 0*08 mm. in length, variable 
in number and in other respects, sometimes reduced to microcalthrops, sometimes to 
microxea, frequently very irregular in form, often reproducing the forms of the meso- 
trisene. 4. SpherasteVy aetines conical, strongylate, often rough or tubercular, confluent 
with the centrum, total diameter 0*0195 mm., numerous. 
Habitat. — Coast of Algiers. 
Remarks. — I owe to the kindness of Professor Perrier a fragment of this interesting 
sponge, but it reached me too late for insertion in its proper place, if, indeed, this, in 
the present state of our knowledge, can be determined ; the Cortex is not fibrous and 
resembles that of Aurora ; pores or oscules I have not seen ; and from the character of 
the cortex I should not expect to find chones ; the mesotrisene is scattered through the 
whole sponge, with a general tendency to lie parallel to the coarse loose bundles of oxeas ; 
the microscleres are generally distributed throughout the whole sponge. 
It appears to me that the mesotrisene may be regarded as a modified orthotriaene, 
which has acquired the habit of growing to maturity within the choanosome, and thus 
presenting among the Stellettidae an analogue to Pcecillastra among the Theneidse. The 
only other sponge in which mesotriaenes are characteristically present is Triptolemus, 
but in this the microscleres are of different character. 
The characters of the chamber system and of the choanosomal rpesoderm are not 
known, and till our knowledge of the sponge is more extensive I regard its precise 
position as uncertain. 
