it is proper for the young shoals to attend them, yet that a few old
ones continue in the rivers so late, that they become perfectly emaciated
by the inconvenience of their situation, and this apparently to guide or to
protect the unexperienced brood.

Of the smaller water animals we have still less knowledge, who nevertheless
probably possess many superior arts; some of these are mentioned in Botanic
Garden, P. I. Add. Note XXVII. and XXVIII. The nympha of the water-moths of
our rivers, which cover themselves with cases of straw, gravel, and shell,
contrive to make their habitations, nearly in equilibrium with the water;
when too heavy, they add a bit of wood or straw; when too light, a bit of
gravel. Edinb. Trans.

All these circumstances bear a near resemblance to the deliberate actions
of human reason.

XV. We have a very imperfect acquaintance with the various tribes of
insects: their occupations, manner of life, and even the number of their
senses, differ from our own, and from each other; but there is reason to
imagine, that those which possess the sense of touch in the most exquisite
degree, and whole occupations require the most constant exertion of their
powers, are induced with a greater proportion or knowledge and ingenuity.

The spiders of this country manufacture nets of various forms, adapted to
various situations, to arrest the flies that are their food; and some of
them have a house or lodging-place in the middle of the net, well contrived
for warmth, security, or concealment. There is a large spider in South
America, who constructs nets of so strong a texture as to entangle small
birds, particularly the humming bird. And in Jamaica there is another
spider, who digs a hole in the earth obliquely downwards, about three
inches in length, and one inch in diameter, this cavity she lines with a
tough thick web, which when taken out resembles a leathern purse: but what
is most curious, this house has a door with hinges, like the operculum of
some sea shells; and herself and family, who tenant this nest, open and
shut the door, whenever they pass or repass. This history was told me, and
the nest with its operculum shewn me by the late Dr. Butt of Bath, who was
some years physician in Jamaica.

The production of these nets is indeed a part of the nature or conformation
of the animal, and their natural use is to supply the place of wings, when
she wishes to remove to another situation. But when she employs th