314 31r. H. J. Ccirter on Squanuilina scopiila, 



longer and more projecting-, until we arrive at the head, which 

 is one mass of entire sponge-spicules of all kinds, arranged 

 very much like pins in a pincushion, viz. with the obtuse or 

 capitate ends, as the case may be, always outwards^ those only 

 being pointed which are pointed at both ends, ex. gr. the spi- 

 cules oi Halichondn'a paiiicca, Johnston, which, either from 

 its being the most plentiful sponge in the locality, or from 

 ])reference of the Squamulina, or both, so far exceed the rest 

 in number, that the animal may be inferred to prefer points 

 to obtuse ends, when it can get them, for its spiculiferous 

 head. 



Not content with grains of quartz and sponge-spicules, we 

 frequently observe other objects, such as chitinous tentacles or 

 setffi of sea-animals, and even filaments of Melosira, incoi-po- 

 rated with the rest of this heterogeneous assemblage. In short, 

 the animal appears to clothe itself wuth every thing of this kind 

 that comes in its way, only confining the e?«<iVe spicules chiefly 

 to the head or free extremity, where one of their purposes is 

 evidently to act as strainers, catching fragments of soft bodies, 

 living or dead, which impinge upon them by sinking or cur- 

 rent-influence, and thus probably entrapping food after the 

 manner of a spider's web, which the pseudopodia then can 

 easily envelope and draw into the body of the SquamuUna. 



Carbonate of lime also enters into the composition of the 

 test ; but this is so trifling in quantity that it is impossible to 

 say if the effervescence does not arise from the presence of 

 fragments of calcareous spicules. Even when dilute nitric 

 acid is applied to the thin disk which is left on the diy fucus, 

 after the superstructm-e may be broken off, the diminution in 

 bulk of the white material appears to be so trifling, although 

 there has been effervescence, that, when dried again, the defi- 

 ciency cannot be appreciated. 



The chitinous substance in which the arenaceous material 

 is fixed is thicker below than it is above, and about the jimc- 

 tion of the column with the summit of the pedestal (tliat is, 

 about the neck) jjresents a fibrous structure which binds the 

 former to the latter by a material at once so tough and resi- 

 lient that the erect or columnar portion may, in the living or 

 wet state, be bent down at right angles to the summit of the 

 pedestal in all directions without breaking or losing its natural 

 elasticity, which, on the other hand, when the pressure is 

 withdrawn, brings the column back to its erect position. 

 Moreover this part, in some specimens, is visibly imcovered for 

 a short distance by the arenaceous coat (fig. 4«), and, I think, 

 as the latitude of its movements in every instance indicates, is 

 always so just at the line of junction with the pedestal. How 



