DISTRIBUTION. 309 DISTRIBUTION OF ANIMALS. early law to which reference has been made. iSWiii- lar statutes have been enacted in all of thi>- United Stales, but these, though governed by the same principles and alike in their general out- lines, vary considerably in detail, in general it may be said that if a man die, leaving a wife and chiidren. one-third of the personal estate goes to the wile and the remaining two-thirds to the children. If there lie a wife and no children, the wife takes (me-half. the other half gning to the next of kin of the deieased. If there lie children and no wife, the children take the whole estate to the exclusion of oilier kindred. In Kngland and in many of our States the position of a sur- viving husband is belter than that of a surviving widow. The old common-law rule, that the hus- band is solely entitled to the personal estate upon the death of the wife, has been generally abro- gated in the United Slates where there are also surviving children, and in many of the States his position has been completely assimilated to that of the wife. For a more detailed and exact state- ment of the order of distribution of intestate's estates, the reader is referred to the statutes of the several States. See the articles on Aniiixis- TKATiox : Descent; Executor ; and the author- ities there referred to; and also Stimson's Ameri- can titatiite Lair, vol. i. (Boston, ISSti). DISTRIBUTION OF ANIMALS, or Zoo- GEOGRAi'iiY. Kniiw ledge of the geographical dis- tribution of animals, and their faunal relations past and present, constitutes a very important part of the science of zoiilogy. An animal's environment exerts a formative inHuence upon its character and structure. Knowledge of its habitat and that of its species, together with such changes as the area and range may have under- gone, is therefore essential to a full understand- ing of the natural history of any kind of animal or animals. Conditions Contbolling Habitat and Kange, Some animals are fitted to dwell wholly upon land, others in water. The aquatic animals are, further, divisible into those of salt and those of fresh waters. The former have the oceans of the world open to them, yet few, if any, range through all seas; furthermore, the inhabitants of the surface of the sea differ from those of its bottom or deeper parts. Similarly, animals able to mount into the air and to fly abroad with apparent freedom, are rarely cosmopolitan, and whole groups of these, as well as innumerable species and individuals, reside only within limited areas or along narrow lines of migratory travel. Fresh-water forms are likely to be re- stricted to separate lakes and river systems. Of the terrestrial animals none are now cosmopoli- tan, except those which have been carried by man to all parts of the world. (The introduced fama of a region must always be distinguished from its indigenous fauna.) On the contrary, each of the present grand divisions of the earth has a characteristic fauna of its OAvn, and often a whole family, order, or even subclass, belongs to one continent alone. Coincident with these restrictions and diversities, likenesses between widely .separated lands are manifest : and repre- sentatives of a single group may be found in regions far distant from one another. To set' forth these facts, to endeavor to account for them, and to develop their significance, is the province of zoiigeogra phy. I.1MIT.S OF DiSI'EBSION; TlIE SEA A.S A MaRRIEB. Each kind of animal must have had a jioint of origin, whence it spread as it increased. Theo- retically, the expansion of a species would pro- ceed eiiually in all directions, but actually this expansion has encountered barriers and restric- tions that have confined and shaped habitats within certain areas, in some instances extremely wide, in others surprisingly narrow. What con- stitutes these barriers and restrictions? That depends in each case on the physical surround- ings as related to the needs and abilities of the animal in question. It is plain that a species of tish that originated in or somehow became restricted to an inland water — Eake Baikal, for example — could never spread beyond its shores save by accidental transplantation; while ain able sea-going fish may wander indefinitely, so tar as mere room is concerned, . ioiig land animals space for expansion, then, is of prime importance. Here the firmest bounds are set by the sea. Any considerable breadth of water, and especially of salt water, is uncrossable except by rare and extraordinary acci<lenl; and even then a pregnant female or a pair must be landed on the further shore in order to start a colony, which must, furthermore, find favorable sur- roundings in order to survive in the new locality. This accounts for the fact that mammals and terrestrial reptiles and amphibians are absent from oceanic islands. Continuity of land, then, is necessary to the spread of a terrestrial species; and when species are found in regions now widely separated, as Europe and Xorth America, it can usually be shown that such regions were formerly connected by lands now submerged. Conversely, the characteristics of the present fauna of" such comparable regions assist the geologist to determine when the connection w'as finally broken. Insilar Faunas. The faunas of most islands near continents date back to the time when these islands were a part of the adjacent mainland, or were separated from it only by narrow straits. The explanation of the broad and conspicuous disparity that exists between- the faunas of such large islands as Australia and Madagascar, and those of Asia and Africa, respectively, is ac- counted for by the evidently very ancient date at which they became dissevered. "It is evident," remark Flower and Lydekker. ■■that Australia has been isolated from the Asiatic Continent from some very remote geological epoch, at which period it is probable that monotremes and marsupials were the dominant if not the sole representatives of the mammalia then existing. Consequently Australia has never been able to receive an influx of the Kutherian orders, which have probably swept away all the marsupials except the small . ierican opossums from the rest of the globe. Again, the large island of Madagascar, which has a fauna of an .frican type, but still very markedly different from that of the mainland, niay be considered to have been connected with the latter at a time when the Eutheria had become the dominant forms, but has been separated for a sulliciently long period to have enabled a large number of its species and genera to have become distinct from those of the adjacent continent. Similarly there is evidence to show that South .America was prob- ably cut off for a considerabh' period from the northern half of the American Continent, in
