ICTLINE OF .Mont.ax CLassmearfox. The earlier writers always classified the animal king dom in a linear series; usually beginning with mankind, and 'descending' to the creatures deemed most inferior. This was net with them, as it is with us. a mere matter of eonvenienee in making a list of the groups, but expressed their belief in the doctrine, unchallenged from antiquity to the time of Lamarck. 1111(1 C' iC1', that there existed what they called a scale nature.. They meant by that their belief that all animals could be arranged in an ascending scale of organization—the infusorians being suc ceeded by polyps, these by radiated forms, these by worms, and so on to fishes, reptiles, birds. and mammals. The. orders within each class, the gen era within each family, conformed to the same scale of increasing complexity; so that a linear classification, from the lower invertebrates to the highest vertebrates, was time expression of their belief in an even progress of structure. Cuvier Tooke into this by his arrangement of the ani mal kingdom. into four groups, unrelated to each other—Radiata, Articulate, and Vertehrata—to be classified in parallel columns, if at all: and this. again, has been super seded by the conception of a form of classi fication which simulates a branching tree. and tries to express a true genetic arrangement, (see PI1YLOGEN ) . the first attempt at which was made by Lamarck. It is. however, impracticable in the present work to attempt such an expres sion of the classification of animals, except for restricted groups; and. in general. the linear
arrangement must be used, bearing in mind that it is a convenient. not a scientific, expression.
The classification outlined below, and fol lowed throughout this Encyclopallia, is that made by Profs. T. Jeffrey Parker and William A. Haswell (Text-Book of Zoology. London and New York, 1897). It is the most complete formu lation of scientific conclusions, has an almost world-wide acceptance, and is generally access ible to students and readers. These considera tions outweigh. for the purposes of a popular encyclopedia, any objections likely to be urged against these authorities by specialists. The advantage of taking and keeping a uniform standard of classilieation and nomenclature throughout a work of this kind is too evident to require argument: and should there be good reason to differ from it, here and there, these exceptions and divergences may easily be treated as they arise. In paleontology this scheme supplemented by the substantially identical clas sification of Zittel-Eastman (Karl A. Vim Zit MiZilyr (1,1- Paliimifolorlic. Alunieh. 1895; translati.d and modified by C. R. Eastman, as Text.linok of l'elcontology, New York and Lon don, ) BOO ) It is needful here only to sketch the arrange ment of the larger groups. leaving the treatment of orders, families. and lesser divisions to be given in the descriptive articles miller the titles of groups, as Itians, Fist!, etc.