li>2 BRITISH SPONGES: 



])roportion of gelatinous fluid which fills the cells and, on dry- 

 ing, forms a thin pellicle at the bottom and on their sides. 



This may possibly be the primary or crustaceous condition of 

 H. aegagropila, but the surface of recent specimens is not coated 

 with a skin, nor does the gelatine on drying foi*m any thing si- 

 milar. The fewness of the siliceous spicula is another remarkable 

 diagnostick, for of this species the mineral ingredient consists 

 principally of small uncrystalline gravel, which is imbedded in 

 the animal matter, and amid which the spicula are almost lost. 



19. H. INCRUSTANS, irregular, extremely porous, rather 

 hard and brittle, like crunih-of-hread or oftener like apiece of 

 old worvi-eaten cork ; oscula obscure, substellated, even xuith 

 the surface ; spicula rather short, needle-shaped, straight 

 or slightly curved. 



Plate XII, Fig. 3. and Plate XIII, Fig. 5. 



Alcyoniumincrustans, i'sjjer, Alcyoji. tab. 15. Lam. Anim. s. Vert. ii. 



397 : 2de edit. ii. 603. Lamour. Cor. Flex. 340. Corall. 244. 

 Spoiigia fava, Montagu in Weni. Mem. ii. 115. Gray, Brit. PI. i. 



360. 

 Spongia paiiicea, Grant in Edin. Phil. Journ. xiii. 104; xiv. 118; 



and in Edin. New Phil. Journ. i. 347 ; ii. 128, 138, pi. 2, fig. 



4, 24, 27- — 29, copied in Blainv. Actinol. pi. 94. 

 Halichondria panicea, Flem. Brit. Anim. 320. 

 Halispongia panicea, Blainv. Actinolog. 532. 



Hah. On rocks within low-water mark. On rocks in the 

 Firth of Forth, abundant ; Island of Staifa, Dr Grant. Scar- 

 borough, Mr Bean. Coast of Devon, not common, Montagu. 

 Plymouth, J. C. Bellamy. Shores of the Isle of Man, Mr E. 

 Fo7-bes. Dublin bay. A: H. Hassall. 



This unattractive species has presented itself to me (1*/) in 

 the form of a thick crust spreading irregularly over the rock ; 

 and (2</) in isolated and detached masses of a roundish shape. 



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