120 



THE SEA SHORE 



If calcareous sponges are to be preserved for future reference, 

 they may be placed in diluted spirit, in which case the animal 

 matter, as well as the mineral substance, will be preserved with 

 but little alteration in the natural appearance and structure. A 

 specimen which has been decalcified by means of acid, as above 

 described, may also be preserved in the same manner ; and small 

 portions of this will serve for the microscopic study of the animal 

 portion of the sponge. If the skeleton only is required, the sponge 

 is simply allowed to dry, when the soft animal substance, on losing 

 its contained water, will leave hardly any residue ; or, better, allow 

 the calcareous sponge to macerate in water for some days for the 



FIG. 68. Grantia compressa 



FIG. 69. SPICULES OF 

 Grantia, MAGNIFIED 



animal substance to decompose, and then, after a few minutes in 

 running water, set it aside to dry. 



Small portions of the skeleton, examined under the microscope, 

 will show the nature of the calcareous spicules of which it is 

 composed. These consist of minute needles and stars, the latter 

 having generally either three or four rays. 



"We give figures of three of the calcareous sponges of our 

 shores, the first of which (Grantia compressa} resembles little 

 oval, flattened bags, which hang pendulous from rocks and weeds, 

 sometimes solitary, but often in clusters. The smaller openings 

 are thickly scattered over the flat sides of the bag, and the larger 



