spider.  Three or four inches above it hovered two minute flies, keeping a little behind, and advancing with it.  The wasp seemed much disturbed by the presence of the tiny flies, and twice left its prey to fly up towards them, but they darted away with it.  As soon as the wasp returned to the spider, there they were hovering over and following it again.  At last, unable to drive away its small tormentors, the wasp reached its burrow and took down the spider, and the two flies stationed themselves one on each side the entrance, and would, doubtless, when the wasp went away to seek another victim, descend and lay their own eggs in the nest.

[Illustration:  WASPS’ NEST.]

[Illustration:  THE SAND-WASP.]

The variety of wasps, as of all other insects, was very great around Santo Domingo.  Many made papery nests, hanging from the undersides of large leaves.  Others hung their open cells underneath verandahs and eaves of houses.  One large black one was particularly abundant about houses, and many people got stung by them.  They also built their pendent nests in the orange and lime trees, and it is not always safe to gather the fruit.  Fortunately they are heavy flyers, and can often be struck down or evaded in their attacks.  They do good where there are gardens, as they feed their young on caterpillars, and are continually hunting for them.  Another species, banded brown and yellow (Polistes carnifex), has similar habits but is not so common.  Bates, in his account of the habits of the sand-wasps at Santarem, on the Amazon, gives an interesting account of the way in which they took a few turns in the air around the hole they had made in the sand before leaving to seek for flies in the forest, apparently to mark well the position of the burrow, so that on their return they might find it without difficulty.  He remarks that this precaution would be said to be instinctive, but that the instinct is no mysterious and unintelligible agent, but a mental process in each individual differing from the same in man only by its unerring certainty.  I had an opportunity of confirming his account of the proceedings of wasps when quitting a locality to which they wished to return, in all but their unerring certainty.  I could not help noting how similar they were to the way in which a man would act who wished to return to some spot not easily found out, and with which he was not previously acquainted.  A specimen of the Polistes carnifex was hunting about for caterpillars in my garden.  I found one about an inch long, and held it out towards it on the point of a stick.  It seized it immediately, and commenced biting it from head to tail, soon reducing the soft body to a mass of pulp.  It rolled up about one-half of it into a ball, and prepared to carry it off.  Being at the time amidst a thick mass of a fine-leaved climbing plant, before flying away, he took note of the place where it was leaving the other half.  To do this, it hovered in front