448 FORAMINIFERA, POLYCYSTINA, AND SPONGES. 



mentions that, in walking over the Small Mouth Sand, which is 

 situated on the north side of Portland Bay, he observed the 

 sand to he distinctly marked with white ridges, many yards in 

 length, running parallel with the edge of the water ; and upon 

 examining portions of these, he found Foraminifera in considera- 

 ble abundance. One of the most fertile sources of supply that 

 our own coasts afford, is the " ouze" of the Oyster-beds, in which 

 large numbers of living specimens will be found; the variety of 

 specific forms, however, is usually not very great. In separating 

 these bodies from the particles of sand, mud, &c., with which 

 they are mixed, various methods may be adopted, in order to 

 shorten the tedious labor of picking them out, one by one, under 

 the Simple Microscope ; and the choice to be made among these 

 will mainly depend upon the condition of the Foraminifera, the 

 importance (or otherwise) of obtaining them alive, and the nature 

 of the substances with which they are mingled. Thus, if it be 

 desired to obtain living specimens from the oyster-ouze, for the 

 examination of their soft parts, or for preservation in a vivarium, 

 much time will be saved by stirring the mud (which should be 

 taken from the surface only of the deposit) in a jar with water, 

 and then allowing it to stand for a few moments ; the finer par- 

 ticles will remain diffused through the liquid, while the heavier 

 will subside ; and as the Foraminifera (in the present case) be- 

 long to the latter category, they will be found almost entirely 

 free from extraneous matter, at the bottom of the vessel, after 

 the operation has been repeated two or three times. It would 

 always be well to examine the first deposit let fall by the water 

 that has been poured away ; as this may contain the smaller and 

 lighter forms of Foraminifera. But supposing that it be only 

 desired to obtain the dead shells from a mass of sand brought up 

 by the dredge, a very different method should be adopted. The 

 whole mass should be exposed for some hours to the heat of an 

 oven, and be turned over several times, until it is found to have 

 been thoroughly dried throughout; and then, after being al- 

 lowed to cool, it should be stirred in a large vessel of water. 

 The chambers of their shells being now occupied by air alone 

 (for the bodies of such as were alive will have shrunk up almost 

 to nothing), the Foraminifera will be the lightest portion of the 

 mass ; and they will be found floating on the water, while the 

 particles of sand, &c., subside. Another method, devised by 

 Mr. Legg, consists in taking advantage of the relative sizes of 

 different kinds of Foraminifera and of the substances that ac- 

 company them. This, which is especially applicable to the sand 

 and rubbish obtainable from sponges (which may be got in large 

 quantity from the sponge merchants), consists in sifting the 

 whole aggregate through successive sieves of wire-gauze, com- 

 mencing with one of ten wires to the inch, which will separate 

 large extraneous particles, and proceeding to those of 20, 40, 70, 

 and 100 wires to the inch, each (especially that of 70) retaining 



