from the Firth of Forth. 79 



the pulpy matter which fills them, and projects through the su- 

 perficial openings, is connected within so as to form one conti- 

 nuous fleshy mass pervading the whole shell. This yellow fleshy 

 substance forms a distinct and well marked zoophyte, which I 

 have termed Cliona celata, and I have not yet found this ani- 

 mal in any other situation than that above described. 



The Cliona in the living state consists of a soft, fleshy granu- 

 lar and distinctly irritable substance, of a greenish yellow colour, 

 traversed Hke many other zoophytes, with minute and regularly 

 formed spicula. Its form depends on that of the cavities which 

 it fills ; it insinuates itself into their minutest ramifications, and 

 adheres so closely to their smooth parietes, that it cannot be se- 

 parated without tearing. The parts of the Cliona which pro- 

 ject through the holes on the surface of the shell are tubular ; 

 and on removing the outer layers of the shell, we can perceive 

 several empty canals winding and ramifying from these tubular 

 papillae, through the body of the zoophyte. During the months 

 of March and April, when these observations were made, nume- 

 rous small yellow ova were seen in the vicinity of the canals, 

 agreeing much in their form, colour, size and mode of distribu- 

 tion with those of the Spongia papillaris and Spongia panicea, 

 which were then nearly in the same stage of advancement. The 

 projecting tubular papillae possess a complicated structure, and 

 a high degree of contractile power, and exhibit a singular series 

 of appearances, when the zoophyte is attentively examined while 

 at rest in pure sea-water. When under water, the papillae are 

 seen projecting from the apertures of the shell, sometimes to the 

 length of a line and a half; they present a wide circular opening 

 in their centre, and a rapid current of water issues constantly 

 from them, conveying occasional flocculi of a grey membrana- 

 ceous matter. But on being touched with a needle, or with- 

 drawn from the water, the opening gradually closes, the current 

 ceases, and the whole papilla continuing slowly to contract, is 

 withdrawn completely within the aperture of the shell. The pa- 

 pillae, viewed in their contracted state, present a smooth, rounded, 

 shut extremity ; but when they begin to advance beyond the sur- 

 face of the shell, their extremity becomes flat and sHghtly di- 

 lated, assumes a villous appearance, with open fissures, radiating 

 ^rom the centre to the margin of the papillae, and at length a mi- 



