« EelmineJätka »
is specially and largely developed in the tropical zone is that of the Chiroptera or lats; which becomes suddenly much less plentiful when we pass into the temperate regions, und still more rare towards the coller parts of it, although it few species appear to reach the Arctic circle. The characteristics of the tropical bats are their great numbers and variety, their large size, and their peculiar forms or habits. In the East those which most attract the traveller's attention are the great fruit-lats, or flying-fuses is they are sometimes called, from the rusty colour of the course fur and the fox-like shape of the head. These creatures may sometimes be seen in immense flocks which take howus to pass by, and they often devastate the fruit plantations of the natives. They are often five feet across the expanded wings, with the body of a proportionate size ; and when resting in the daytime on dead trees, hanging head downwarils, the branches look as if covered with some monster fruits. The descendants of the Portuguese in the East use them for fool, but all the native inhabitants reject them.
In South America there is a group of bits which itre sure to attract attention. These are the vam ures, Se voral of which are blooil-sucking species, which abound in most parts of tropical America and are especially plentiful in the Amazon Valley. Their carnivorous propensities were once discredited, but are too well authenticate. Horses and caitle are often bitten, and are found in the morning covered with blood ; and repeatul attacks weaken and ultimately destroy them. Some persons are especially subject to the attacks of these bats; and as native huts are never suficiently close to keep them out, these unfortunate imividuals are obliged to sleep completely muffled up, in order to avoid being made seriously ill or even losing their lives. The exact manner in which the attack is made is not positively known as the suflirer never feels the wound. The present writer wils once bitten on the toe, which was found bleeding in the morning from a small round hole from which the flow of blood was not easily stopped. On another occasion, when his feet were carefully covered up, he was bitten on the tip of the nose, only awaking to find his face streaming with blood. The motion of the wings fans the sleeper into a deeper slumber, and renders him insensible to the gentle abrasion of the skin cither by teeth or tongue. This ultimately forins a minute hole, the blood flowing from which is sucked or lipped up by the lovering vampire. The largest South American bats, having wings from two to two-and-half feet in expanse, ire fruit-caters like the Pteropi of the East, the true blood-suckers being small or of medium size and varying in colour in different localities. They belong to the genus Phyllostomi, and have a tongue with horny pipillie at the end; and it is probably by means of this that they abrade the skin and procluce a small round Wound. This is the account given by Buffon and Azara, and there seems now little doubt that it is correct.
Beyond these two great types—the monkeys and the Witz-We look in vain among the varied forms of mammalian life for any that can be said to be distinctive of the tropics is compared with the temperate regions. Many peruliar groups are tropical, but they are in almost every case contined to limited portions of the tropical zones, or are rare in species or individuals. Such are the lemur's in Mrica, Madagascar, and Southern Asia; the
tipirs of America and Malaya; the rhinoceroses and clephants of Africa and Asia; the cavies and the sloths of America; the scaly ant-eaters of Africa and Asia; but none of these are sufficiently numerous to come otion before the traveller so as to all'ect his general ideas of the aspects of tropical life, and they are, therefore, ollt of place in such a sketch of those aspects as we are here attempting to lay before our readers.
Summary of the aspects of Animal Life in the Tropics. We will now brietly summarize the general. asperts of animal life as forming an ingredient in the scenery and natural phenomena of the cquatorial regions. Must prominent are the butterflies, owing to their numbers, their size, and their brilliant colours ; as well as their peculiarities of form, and the slow and majestic flight of many of them. In other insects, the large size, and frequency of protective colours and markings are prominent features; toor.ther with the inexlaustible profusion of the ants and other small insects. Among birols the parrots stand forth is the pre-eminent tropical group', as do the apes and monkeys among mammals ; the two groups having striking analogies, in the prehensile hand and the power of imitation. Of reptiles, the two most prominent groups are the lizards and the frogs; the snakes, though equally abundant, being much less obtrusive.
Animal life is, on the whole, far more abundant and more varied within the tropics than in any other part of the globe, and a great number of peculiar groups are found there which never extend into temperate regions. Endless cecentricities of form, and extreme richness of
colour are its most prominent features; and these are manifested in the highest degree in those equatorial lands where the vegetation acquires its greatest beauty and its fullest development. The causes of these essentially tropical features are not to be found in the comperatively simple influence of solar light and heat, but rather in the uniformity and permanence with which these and all other terrestrial con«litions have acted ; neither varying prejudicially throughout the year, nor having undergone any important change for countless past ages. While successive glacial periods bile devise tated the temperate zones, anel destroyed most of the larger and more specialized forms which during more favourable cpochis has been developed, the cquatorial lands must always have remained thronged with life; and have been unintermittingly subject to those complex influences of organism upon organism, which seem the main agents in developing the greatest variety of forms and filling up every vacant place in nature. A constant struggle against the vicissitudes and recurring severities of climate must always have restricted the range of effective animal variation in the temperate and frigid zones, and have checked all such developments of form and colour as were in the least degree injurious in themselves, or which co-existed with any constitutional incapacity to resist great changes of temperature or other unfavourable conditions. Such disadvantages were not experienced in the equatorial zone. The struggle for existence as against the forces of nature was there always less severe, -food was there more abundant and more regularly supplied, -shelter and concealment were at all times more casily obtained; and alınost the only physical
changes experienced, being dependent on cosmical or geological changes, were so slow, that variation and natural selection were always alile to beep the tecming mass of organisms in nicely balanced harmony with the changing physical conditions. The equatorial zone, in short, exhibits to us the result of a comparatively continuous il inchecked development of organic forms; while in the temperate regions, there have been a series of periodical checks and extinctions of a more or less lisastrous bature, necessitating the commencement of the work of development in certain lines over and over again. In the one, evolution has lad a fair chance; in the other it has had countless illiculties thrown in its way. The cquatorial regions are then, ils regards their past and present life history, a more ancient world than that represented by the temperate zones, a world in which the laws which have governed the progressive development of life have operated with comparatively little check for countless ages, and have resulted in those infinitely varied and beautiful forms—those wonderful cocentricities of structure, of function, and of instinctThat rich variety of colour, and that nicely balanced harmony of relations which delight and astonish us in the animal productions of all tropical countries.