208 LIVERPOOL BIOLOGICAL SOCIETY. 



same genus, Plumohallchondrla plmnosa, Carter, having 

 previously been obtained at Holyhead.* I found it at 

 Puffin Island, April, 1889, and at Hilbre Island, May 

 1889, a short way above low- water mark. 



Bowerbank f records it from St. Katherine's Cave, 

 Tenby ; rocks off Hastings ; Guliot Caves, Sark ; Lennen 

 Cove, Land's End, Cornwall, and he describes the external 

 appearance of this sponge in the following words : — " Its 

 appearance is that of a small patch from one to two inches 

 in diameter, of dark clot of blood adhering closely to the 

 surface of the rock, and it can be obtained only by cutting 

 away the piece of stone to which it adheres. It rarely 

 exceeds about half a line in thickness. Its extreme thin- 

 ness readily distinguishes it from the deep red coloured 

 sponge, Clial'ma scrlata,^ which occurs abundantly along 

 with it in that cave (at St. Katherine's Island, Tenby), 

 and which is so thick as to be easily removed from the 

 rock with a knife." Bowerbank's description applies very 

 well to the condition in which I found this form, together 

 with Clathrla seriata, at Puffin Island. In order to get 

 sections of Plamolialichondria atrasdngaiaea one has to 

 remove a portion of the rock (carbonate of lime) together 

 with the sponge, and dissolve the former with acids. 

 Specimens from Hilbre Island are of less use for histologi- 

 cal purposes because the rocks there consist of sandstone. 



The ceratose skeleton of our species consists of a limit- 

 ing membrane which is closely applied to the rock, and 

 of ascending fibres, arising about at right angles from the 

 limiting membrane. Those fibres are furnished abundantly 

 with echinating megascleres of two kinds ; there are styli 



* Thomas Higgiii, "Report on tlie rorii'era," in "Fauna of Liverpool 

 Bay," p. 78. 



t Bowerliaiik, " British Spoiigiadae," vol. ii,, p. 139. 



§ Chalina seriata is identical with Clathria seriata, see }). 205. 



