Halichondria. ZOOPHYTA. SPONGIAD^. 521 



Crust extended sometimes an inch in thickness ; when dried, the surface 

 is flat and very porous, and the orifices, which are rather sunk, have irregu- 

 lar margins, and the divisions of the interior canals being usually visible, 

 give the openings a stellular aspect. When dry, it is remarkably friable. I 

 am inclined to consider this species as the S. fava of Montagu, Wern. Mem. 

 ii. 115. He says, "This sponge, though harsh to the feel, yields to the 

 pressure of the finger nail without elasticity ; when recent is orange- yellow, 

 and full of gelatinous flesh, but when exposed for a time on the shore, and 

 the fleshy parts decayed and washed out, the pores are observed to be round- 

 ish. When examined by a lens, has a slight resemblance to a honey -comb ; 

 the pores, however, are not regular in size. If taken fresh and artificially 

 dried, the pores are greatly obscured by the contracted gluten, and the colour 

 becomes of a dark brown. If it has undergone a natural decomposition of 

 the more perishable parts on the sea-shore, by the conjoined action of the 

 water and the air, the pores are cleared, and it retains a light yellowish co- 

 lour. A specimen in this state before me, is flat and broad ; round the edges 

 (which appear to have been broken) there are many large round openings in- 

 tersecting the smaller pores, and communicating with those on the flat sur- 

 faces. This piece is three inches long, two broad, and about half an inch 

 thick. 



• 95. H. parasitica. — Substance rather loose, harsh to the feel, 



and somewhat brittle ; spicula shghtly curved, and pointed at 



one extremity. 



Mont. Wern. Mem. ii. 114 Investing fuel and corallines, not uncom- 

 mon. 



Surface rough, with the extremities of fasciculated spicula ; pores angu- 

 lar, unequal ; orifices scattered, slightly elevated , with the margins not 

 thickened. 



96. H. cinerea. — Three inches long and one broad, circular, a 



little depressed ; pores minute, unequal ; orifices scattered, few, 



spicula short, curved, and double pointed. 



Spongia cin. Gi-ant., Edin. New Phil. Journ. ii. t. ii. f. 3. — On rocks, 

 Frith of Forth, rare. 



About half an inch thick, blackish-grey, the surface smooth, convex, fleshy 

 and transparent. 



97. H. columba. — Irregularly latticed by rounded inoscula- 

 ting branches ; spicula double pointed and curved. 



Spongia col. Walker'' s Essays, 1 26 — S. cancellata. Sower. Brit. Misc. i. 

 131, t. vi — Icolumbkil, Dr Walker ; Brighton, Mr Fellows. 

 Branches about a quarter of an inch thick ; pores minute, angular ; the 

 orifices, seated chiefly at the union of the branches, are conical, wide, with 

 the margins not thickened. As this species is different from either the S. 

 cancellata of Gmelin or Lamarck, I have ventured to change the name, im- 

 posed by Mr Sowerby, for the term employed by Dr Walker, in the convic- 

 tion that the sponge referred to by both is identical. 



98. H. sanguinea. — Colour deep blood-red, encrusting ; spi- 

 cula long, curved, single-pointed. 



Spongia sanguinea, Grant., Edin. New Phil. Journ. ii. t. ii. f. 9. — Shores 

 of the Plebridea. 

 Crust on the under surface of exposed rocks, sometimes six inches in dia- 

 meter, and with a thickness of more than liulf an inch ; general surface flat. 



