Not less care should be taken to collect the land shells as those of the sea. Fossil shells are likewise of great interest.
Very frail shells, oursins, sea-stars, etc., should be wrapped in cotton and placed, each one apart in a box. It would be well to wash in chalk water oursins and sea-stars; the greatest number possible of these animals should be preserved in spirits of wine, taking care to surround them with thread, or even fine linen or cotton, and, afterwards, wound with thicker linen or several turns of thread, so as to hinder the points or spines from falling. The madrepores of a certain volume should be fixed by wire to the bottom of the box in which they are placed, but these frail substances would arrive in better order, if each specimen was placed in a box apart.
The shell-fish should be placed in alcohol. The outer shell, when it is spiral, should be broken at the upper part, and at several points of the spire, to let the liquor run in, so that the whole animal may be preserved; it is possible, following this indication, to have shell-fish in such order, that they may be dissected, even after being a very long time in the collections.
In calm or gentle breezes, it is well to have ready a gauze net to seize the sea molluscs, whose number is considerable. They should be watched and drawn several times a night, for it is probable that the spirule will be found at the surface of the water. Fishes should be opened to find this same spirule which is doubtless caught by them; the other Cephalopodes are not less numerous or less curious to study.
There is a class of being called marine worms or Annelides, of which but a few kinds are known, because little pains have been taken to collect them; these animals frequent generally the shores of the sea, a great number live in the interstices of madrepores, several make deep holes in the sand or in the mud. With spades and hammers they could be easily procured; it would be necessary to preserve them in alcohol, as the greatest part of these kinds make themselves sheaths, it would be well to collect them and put them in spirits of wine. Ordinarily these animals quickly change color; it would be well to note their color; it would be always well to do this for the leeches, whose colors disappear as soon as they are dead. The attention of naturalists should be directed towards the lombrics or earth-worms. These animals could be sent us alive as well as all the land molluscs, by sending them in closed boxes containing a little earth or damp moss.
It would be well to look for the entozoaires or helminthes of different animals and send them, declaring at the same time the animal and viscera whence the worm is extracted.
Articulated animals.—Articulated animals (viz. insects, spiders, crustacees, etc.), compose the principal family of the animal kingdom; collections made in distant countries include generally a considerable proportion of new-varieties and the capture, preservation and transport of these little beings offer no serious difficulties. We recommend in a special manner to the attention of travellers enthomological researches; undertaken with zeal and intelligence, even by a person who is not a naturalist, they can not fail of being useful to science and important for the museum. In this, as in the other branches of zoology, it is not only the large and brilliant kinds which are more valued by the naturalist; generally it is, on the contrary, among the small insects or those of plain colors that the more novel forms are found; for collectors have ordinarily neglected them, and even in the best explored regions (in the environs of Paris, for example) are discovered varieties which, till now, have escaped attention. As for the manner of forming these collections and the particular indications relative to the classes into which is divided this vast division of the animal kingdom, and, consequently, we shall give to each of these groups a separate article.
Insects.—What we have said of articulated animals in general, is particularly applicable to insects, whose number is immense, and whose forms vary beyond all imagination. The kinds differ extremely from one country to another, often even from one locality to another, and it is rare to find perfect identity between insects which inhabit different regions, though often, at the first glance, no difference can be detected between them; besides, there is no point on the globe, where the enthomologic Faun is completly known, and although our museum has about eighty thousand kinds, our galleries do not include half that are seen in looking through the different collections of Europe. It results that, in all countries, travellers who occupy themselves with enthomology, can render themselves useful to the museum, and, in distant countries, they should not neglect collecting all the insects they find, even when the kinds do not appear to differ in anything from those found every day at home. There are some parts of the globe, which, enthomologically, deserve to fix the attention of the collecter, either by reason of their extraordinary richness or on account of the small number of parcels yet sent to the museum. Such are: the west part of Africa, from the gulf of Beninso the cape of good Hope; the Birman Empire, Assan, and even the interior of India, whence the English enthomologist receive so many remarkable varieties; Borneo, the Phillipines and the neighbouring isles; the western and northern part of Australia; the west coast of North America, from Mexico to Behring's strait, and the great basins of the Amazon.
In general entomologists content themselves with collecting insects without studying the manners and mode of life of these animals; yet they thus fulfill but a part of their duty, for it is necessary for the progress of science to have exact notions on this subject. Thus, it is well to indicate, whenever it is possible, not only the locality where the insect is found, but, besides, the nature of the locality, the names of the plants on which the variety is found, and all the particulars relative to its manner of life. It would be interesting to have samples of the products of the industry of these little beings, the nest of bees and ants, the combs of wild bees, cocoons, etc. The stuffs supplied by insects and used in the arts, are equally important to collect and study with regard to their mode of production. Besides, we shall call the attention of travellers to the alteration made by insects in the plants they inhabit, the manner many of them pierce the bark of trees or even the wood, eat or roll the leaves, or cause in them, by their stings escrescences, etc. Specimens of these alterations would be of great interest to enthomology, especially when united with the insect that occasions them.
We urge travellers, likewise, to look for cheniles and the other larvæ, and to preserve some of them alive, in order to obtain a perfect insect, or, at least, a crysalis. Larvæ whose origin is unknown would be of scarce any interest to the museum, while a collection in which each larvæ is united whith the perfect insect would be of great interest.