It is an old and a true saying that you "can have too much of a good thing." A London alderman would soon grumble had he to dine every day on turtle only. "The great fresh-water turtle of the Amazons grows in the upper river to an immense size, a full-grown one measuring nearly three feet in length by two in breadth, and is a load for the strongest Indian. . . . . The flesh is very tender, palatable, and wholesome; but it is very cloying. Every one ends sooner or later by becoming thoroughly surfeited." Our traveller adds that he became so sick of turtle in the course of two years that he could not bear the smell of it, although at the same time nothing else was to be had, and he was suffering actual hunger. The pools about Ega abound in turtles and alligators, and the Indians capture a great number of the former animals by means of sharp steel-pointed arrows, fitted into a peg which enters the tip of the shaft. This peg is fastened to the arrow-shaft by means of a piece of twine; and when the missile--which the people hurl with astonishing skill--pierces the carapace, the peg drops out and the struck turtle dives to the bottom, the detached shaft floating on the surface serving to guide the sportsman to his game. So clever are the natives in the use of the bow and arrow, that they do not wait till the turtle comes to the surface to breathe, but shoot at the back of the animal as it moves under the water, and hardly ever fail to pierce the submerged shell. One of the most curious and interesting facts in natural history is the assimilation in many animals of form and color to other objects, animate or inanimate. Thus the caterpillars termed, from their mode of progression, "geometric" bear so close a resemblance to the twigs of the trees or bushes upon which they rest that it is no easy thing to distinguish them at a {190} glance; the buff-tip moth, when at rest, looks just like a broken bit of lichen-covered branch, the colored tips of the wings resembling a section of the wood. The beautiful Australian parakeets, known as the Batcherrygar parrots, look so much like the leaves of _Eucalpyti_, or gum-trees, on which they repose, that, though numbers may be perched upon a branch, they are hardly to be seen so long as they keep quiet. Some South American beetles (of the family _Cassidae_) closely resemble glittering drops of dew; some kinds of spiders mimic flower-buds, "and station themselves motionless in the axils of leaves and other parts of plants to wait for their victims." Insects belonging to the genera of _Mantis, Locusta_, and _Phasma_, often show a wonderful resemblance to leaves or sticks. Examples of "mimetic analogy" may also be found amongst birds; but perhaps the most remarkable cases of imitation are to be found among the butterflies of the valley of the Amazon recently made known to us by Mr. Bates. There is a family of butterflies named _Heliconidae_, of a slow flight and feeble structure, very numerous in this South