PORIFERA OF THE L.M.B.C. DISTRICT. 229 
dra ciliata, which was attached to the surface of the 
Stelletta. The prionorrhabds are arranged radiately, the 
ideal centre of the circle lying inside the Sycandra. But 
only this one small portion of the Stelletta, opposite to 
which the Sycandra is situated, shows those spicules. 
As this special kind of spicule has never before been 
described in Stelletta collingsi, nor in any other sponge, the 
question arises whether my specimen is identical at all 
with St. collingsi or whether the spicules are present in all 
specimens of St. collingsi and have been overlooked by 
former investigators, or lastly, whether they are a special 
acquirement which may become developed in the sponge 
under certain conditions. I am inclined to accept the last 
of the three views. Ihave mentioned already that the pri- 
onorrhabds were found only in a certain portion of Stelletta, 
and I believe that they have been acquired by the sponge 
under the special abnormal conditions to protect itself 
against the encroaching foreign body, a calcareous sponge. 
As in my specimen they are very localized, it is quite 
possible that they have been overlooked by other workers. 
I collected several specimens of Stelletta collingsi at Puffin 
Island, in one of the caves on the north end of the island, 
in April, 1889. One specimen had been found there already, 
in June, 1888. The colour of the living specimen is 
ereyish-white. 
Puchymatisma johnstonia, Bowerbank. 
The colour of this species is known to be subject to 
ereat variation. Bowerbank* states—‘“‘ Littoral specimens, 
light to dark slate-grey. Deep sea specimens, pink or 
ved.’ And Sollas+ says—‘“‘ Slate-grey on the portion ex- 
posed to the light, almost white beneath; specimens from 
~ * Bowerbank, “‘ British Spongiadz,” vol. ii., p. 51. 
+ Sollas, ‘Report on the Tetractinellida,” collected by H.M.S, ‘‘ Chal- 
lenger,” p. 248, 
