_Land and Freshwater Mollusca._[14] Full instructions for collecting these will be found in the ‘British Museum Handbook,’ pp. 113-115. Lieut.-Col. H. H. Godwin-Austen, F.R.S., has contributed the following notes on collecting these animals: Mollusca are always most abundant on limestone rocks, and should be searched for under the larger stones lying about the ground, and under fallen trees and logs in the woods and forests. They may generally be found adhering to the surface of the stone or wood. Many species are often only 0.05 inch in length, so that very close examination is necessary. In damp spots, generally in ravines with a northerly aspect, the dead leaves when damp with dew in the early morning may be turned over one by one, and the under surface examined for minute species; larger species will be found very frequently on the surface of the ground below the layer of decaying vegetable matter. Many may also be secured by tearing off the bark of decaying trees. In the drier parts of the country some species are only to be found among the roots of shrubs, at considerable depth; by digging these up and shaking the earth on to paper, small shells may be found on close examination. At a dry place like Aden, I should expect to find most of the living land-shells in such a habitat. Look well in limestone caves on the damp surface of the rock; some forms hide themselves under a coating of earthy matter. Search also on damp moss and rocks near waterfalls. Some species will be found high up on the bushes and trees. This is the habit of certain African forms especially; not so in India. A very good idea of the land-shells of a country may at first be obtained by the examination of the beds of the streams, either along the highest flood-line, or in the fine sand and mud collected in the bed. Land-shells found in such situations are usually old and bleached, but the living specimens will not be far off. The leaves and stems of water plants should be examined, and Confervæ taken out of the water and well washed in a basin; in these, and in the mud of ponds and still rivers, many minute shells may be found. The best way of preserving minute shells is to put them into glass tubes plugged with wool; it is better than cork. Capital collecting tubes can be made out of the smaller sorts of bamboo and the large grasses. A certain number of every species (at least a dozen) should be preserved in spirits for the sake of the anatomy. It is best to kill them first in water and then put them into spirits; if this is not done they contract, so that it is impossible to form any idea of the form of the mantle and other parts, and they become so hard they are difficult to cut up. A good method of keeping the small shells and slugs, especially in spirits, is to put them with labels into small tubes plugged with wool, and then place the tubes in a large jar, capable of holding three or four dozen.