222 _ LIVERPOOL BIOLOGICAL SOCIETY. 
Stellettid by its own basal membrane, and the Stellettid 
from the Suberite by its outer epithelium, distinguished 
in favourable parts of the sections by the somewhat dense 
layer of sanidasters which usually are more crowded there 
than elsewhere. The basal membrane of the Suberite 
supports the heads of the longer tylostyles as so commonly 
happens in these sponges.”’ Curiously enough Déderlein * 
fell into a quite similar error in regard to Discodermia calyz, 
D., and Bowerbank + in regard to Stelletta collingsi, B., 
and Stelletta schmidte:, B. As, notwithstanding the above 
stated error, the encrusted tetractinellid sponge is new to 
science, and is the only representative of a new genus, 
Seiriola,t I propose to give now a corrected description of 
it. No new figure of the spicules will be necessary, as I 
can refer to Vol. III., Pl. VII., where, however, no notice 
should be taken of the upper thinner layer which does not 
belong to Seriola compacta. This foreign layer is cha- 
racterized by tylostylote spicules and is separated from the 
lower portion, the Seviola compacta, by a definite line of 
demarcation. It belongs to a monaxonid sponge, Suberites 
domuncula, Nardo. 
The first specimen of Seiriola compacta was found at 
Puffin Island, in June, 1888, in one of the caves on the 
north-east side of the island, which are exposed only at 
low spring tides, and then accessible only by boat. It 
formed a knob-lke mass, like that of so many tetractinellid 
sponges, and measured horizontally 4 cm. by 1°5 em., and 
vertically 1°3 cm. It came into my hands after it had 
been in rather weak spirit for several weeks, and was then 
* Sollas, ‘‘ Report on the Tetractinellida,” collected by H.M.S. ‘‘Chal- 
lenger,” p. 295. 
+ Sollas, loc. cit., p. 186. 
+ From Seiriol, an early Welsh saint, who is said to have had his eell on 
Puffin Island, 
a ——— ee ee eee 
