136 BRITISH SPONGES; 



Sponge rooted at various points, homogeneous, diffused, much 

 and irregularly branched, the branches distorted, anastomosing, 

 roundish, or more or less compressed, and often subcarinated at 

 the sides, where a few porous tubercles are sometimes observed : 

 structui'e compact, friable and inelastic when dried, cellular in- 

 ternally, the surface somewhat pitted or rugose, but its pores 

 are scarcely visible without a magnifier ; colour grayish-white. 

 Spicula very abundant and various in size, — the larger ones fu- 

 siform, and usually somewhat curved, — the slenderer ones 

 linear, sharp-pointed, either straight, or variously bent. " In 

 the S. coalita, besides the slender-curved fusiform spiculvun, we 

 observe a long thick spiculum of the same form, which extends 

 along the sides of two or three successive pores, and contributes 

 much to their strength in a species peculiarly liable to have the 

 diameter of those passages disturbed from the flexibility of its 

 branches, * and their erect position at the bottom of the sea." 

 Grant. 



" WTien the coalita is young, its branches are long and 

 slender ; they shoot in all directions to seek for points of at- 

 tachment, and adhere to, or envelope, everything they meet 

 with, living or dead, animal, vegetable, or mineral ; wherever 

 the branches cross or touch each other, they form a perfect 

 union ; sometimes the animal spreads as a layer over an oyster- 

 shell, or covers a rock like a convoluted bush, or like the root 

 of a fucus, or forms a cement, connecting into a mass all man- 

 ner of shells, stones, or broken glass ; sometimes it forms an ir- 

 regular mass, with a perfectly smooth surface, without any 

 point of attachment, rolling to and fro, at the mercy of the 

 waves. As it advances in life, its colour assumes a darker 

 shade, with a tinge of brown ; it becomes less smooth on the 



* In a dried state the branches are brittle ; nor do they ever grow 

 erect, in the proper sense of tlie word. 



