222 LIVEEPOOL BIOLOGICAL SOCIETY. 



Stellettid by its own basal membrane, and the Stellettid 

 from the Suberite by its outer epitheHum, 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 Doderlein * 

 fell into a quite similar error in regard to Discodermia calyx, 

 D., and Bowerbank t in regard to Stelletta colUngsl, B., 

 and Stelletta schmidtei, 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,l 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., PI. YII., where, however, no notice 

 should be taken of the upper thinner layer which does not 

 belong to Seiriola compada. This foreign layer is cha- 

 racterized by tylostylote spicules and is separated from the 

 lower portion, the Seiriola compacta, by a definite line of 

 demarcation. It belongs to a monaxonid sponge. Saber ites 

 domnncula, 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-like mass, like that of so many tetractinellid 

 sponges, and measured horizontally 4 cm. by 1"5 cm., 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 Tetractinollida," collected by H.M.S. "Chal- 

 lenger," p. 295. 



t Sollas, loc. cit., p. 186. 



X From Seiriol, an early Welsh saint, who is said to have had his cell on 

 PiitHn Island. 



