D294 LIVERPOOL BIOLOGICAL SOCIETY. 
and sanidasters (not spirasters, as I called them in my 
previous report) 0°012 to 0°016 mm. in length, and are 
both very typical forms. The oxyasters are found only in 
the choanosome, the sanidasters chiefly in the ectosome, 
and a few also in the choanosome. 
Besides those megascleres and microscleres, I found 
fragments of a third kind of spicule (see fig. 2 c., Pl. VIL., 
Vol. III.), the appearance of which, in my former report, I 
compared with broken blades of fret saws. The largest of 
these pieces measured 0:08 by 0:0014 mm. They were 
found just beneath the surface of the sponge. But now L 
think it quite possible that they do not belong to Seriola 
at all, but rather to Stelletta collings:, in which latter sponge 
I now describe them for the first time (see Pl. XIV., 
figs. 1 and 2). As my specimens of Seriola and Stelletta 
had been taken from the same rock, and had been kept 
together for some time in the same jar of spirits, 1t 1s pos- 
sible that fragments of those spicules found their way acci- 
dentally into the Secrzola. 
Oscula and pores could not be distinctly seen, neither 
in the living specimens nor in sections. The incurrent 
and excurrent canals seem to branch in a very irregular 
manner through the sponge. The chamber-system ap- 
pears to belong to the eurypylous type,* in so far as the 
flagellated chambers he closely round the excurrent canals, 
and as the apopyles are not continued into special tubes 
and are extremely short. At the same time the term 
‘““eurypylous”’ does not apply correctly to Sezriola, as the 
apopyles are extremely narrow. ‘The flagellated chambers 
and collar cells are very small. The former are oval, and 
measure 0°012 by 0°008 mm. The collar cells measure 
0:0013 mm. 
The mesoderm of Se‘riola consists of sarcenchym, the 
* Sollas, loc. cit., p. xv. 
