BRITISH SPONGIADiE. 77 



divided at right angles to the axis of the fruit, and placed 

 with the convex- portion uppermost ; and like the fruit it 

 has a depression in the middle of the upper surface, from 

 the centre of which springs the pedicel, which has its 

 greatest contraction at its junction with the base of the 

 sponge, from which part it increases gradually upwards, 

 and finally enlarges into the pyriform distal termination. 

 The attachment of the proximal end of the pedicel with 

 the expanded base of the sponge is very singular. In 

 some cases, I observed the end of the pedicel did not 

 appear to be an open tube springing from the circular line 

 of junction in the base of the sponge ; but, on the con- 

 trary, it was contracted and apparently closed in a hemis- 

 pherical form, and it looked as if it had been fixed into the 

 base by having been, as it were, plugged into a previously 

 existing hole on its summit, and the external and internal 

 junction lines were sharp and angular. From this point 

 upwards the pedicel gradually enlarges until it expands 

 into the pyriform head. The whole sponge, the hassock- 

 shaped base, .as well as the pedicel and head, are hollow, 

 and the thickness of the parietes is very inconsiderable. 



The arrangement of the spicula of the skeleton in the 

 base is decidedly irregularly reticular, and it is singular 

 that the network in almost every case appears to be com- 

 posed of fragments instead of perfect spicula. 



In the pedicel, the spicula are dispersed, with very few 

 exceptions, in lines parallel to the long axis of the sponge, 

 and the short acerate spicula are more especially found in 

 this part. Intermixed with the spicula of the pedicel there 

 are frequently grains of sand and other extraneous matter 

 embedded, apparently to increase its strength, and this 

 intermixture more particularly occurs in the elongated ones. 

 Occasionally, very stout and large spicula are found in the 

 pedicel, and in one case an exceedingly large and stout 

 triradiate one projected one of its rays at right angles 

 from its axis, the other two running nearly parallel to the 

 axial line of the pedicel. The head of the sponge is abun- 

 dantly furnished with defensive spicula which radiate in all 

 directions between lines in accordance with, or at right angles 



