BRITISH SPONGIAD/E. 29 



inch iii diameter ; and if these be carefully examined they 

 will be found to consist of numerous individuals congre- 

 gated together, and not of one complex sponge, as at first 

 sight they might readily be thought to be. In the young 

 state they appear as short unbranched cylinders, or with a 

 single terminal branch ; others have two, three, or more 

 short branches, each usually having a terminal cloacal 

 mouth, but it is rather unusual to find them as much 

 branched as the specimens represented by Ellis and Dr. 

 Johnston. However much branched, there is never but 

 one cloacal cavity, which extends throughout the whole of 

 the sponge. The defensive radii within the cloaca are 

 numerous, and many of them as long as nearly half the 

 diameter of that organ, and they are slightly curved near 

 the points in the direction of its mouth. The pores may 

 be seen in dried specimens when viewed with a power of 

 about 150 linear by direct light ; but when the interior sur- 

 face is examined, either by direct light or when mounted 

 in Canada balsam by transmitted light, it is very difficult to 

 detect any regular orifice in the form of an osculum. The 

 spicula of the skeleton, as compared with those of Leucosolenia 

 contorta, the only known British species with which this 

 sponge is liable to be confounded, are comparatively short 

 and stout, and their radii, unlike those of L. contorta, 

 decrease rapidly in diameter from the base to the apex. 

 Ellis's figure of the spicula of Sjjongla botryoides is very 

 correct. 



2. Leucosolenia contorta, Bowerbank . 



Sponge. Sessile, a mass of contorted anastomosing fistula? ; 

 parietes thin ; surface smooth, with a few procumbent 

 acerate spicula. Cloaca very large, continuous, armed 

 internally with spiculated, equiangular, triradiate 

 spicula; spicular ray short, stout, slightly curved; 

 mouths numerous, simple, and unarmed. Oscula and 

 pores inconspicuous. Spicula of skeleton equiangular 



