That Garrod has so very much advanced the classification of birds is ultimately due to his comprehensive anatomical knowledge and general insight.
It is certain, however, that no such classification can be considered final at present, but must undergo continual revision in the future.
It would be impracticable to go fully into the varieties of each specific form; but, partly as an example of modern geographical classification, partly because of the exceptional import of ance of mountains amongst the features of the land, one exception may be made.
Whilst the type of syrinx affords no help in classification, it is very different with its muscles.
Huxley, " On the Classification of Birds and on the Taxonomic Value of the Modifications of certain of the Cranial Bones..."
This way of using the characters of the syrinx for the classification of the Passeriformes seems simple, but it took a long time to accomplish.
The Code ") has, however, made a more systematic study possible than could have resulted from the classification and interpretation of the other material.
Latin and its nearest congeners, like Faliscan); and (d) Umbrian (or, as it may more safely be called, Iguvine), two principles of classification offer themselves, of which the first is purely linguistic, the second linguistic and topographical.
The two kinds of persons present in the typical Hydroidea make the classification of the group extremely difficult, for reasons explained above.
As in the Gymnoblastea, the difficulty of uniting the hydroid and medusan systems into one scheme of classification is very great in the present state of our knowledge.
The varieties of coast-lines were reduced to an exact classification by Richthofen, who grouped them according to the height and slope of the land into cliff-coasts (Steilkiisten)- narrow beach coasts with cliffs, wide beach coasts with cliffs, and 1 Rumpf, in German, the language in which this distinction was first made.
A subject so vast and so incapable of classification cannot be discussed here, but its aesthetic principles may be illustrated by the extreme case of the trumpets and horns, which in classical times had no scale except that of the natural harmonic series.
A natural classification of the Hydroidea has yet to be put forward.
Such a system of classification, although convenient, is not the most natural one, and a sketch of the system which better expresses the relationships between the various subdivisions is given here.
The above classification by Warming, although it was without doubt the best ecological classification which had, at the time, been put forward, has not escaped criticism.
The classification of the land surface into areas inhabited by distinctive groups of plants has been attempted by many phytogeographers, but without resulting in any scheme of general acceptance.
The few characters assigned to the various groups are sufficiently diagnostic when taken together, although they are not always those upon which the classification has been established: - Class Aves I.
The classification given here is for the most part that of Delage and Herouard.
When the nature and effect of ecological factors have become more fully understood, it will be possible to dispense with the above artificial classification of factors, and to frame one depending on the action of the various factors; but such a classification is not possible in the present state of knowledge.
From the point of view of the economy of the globe this classification by species is perhaps less important than that by mode of life and physiological character in accordance with environment.
Blanchard, " Recherches sur les caracteres osteologiques des oiseaux appliques a la classification," Ann.
A statement may now be given of Gadow's classification of birds, in which the extinct forms have been intercalated so far as possible.
It is probable that further research will amend this classification in detail, but its main lines are generally accepted.
But at present the word "leech" is applied to every member of the group Hirudinea, for the general structure and classification of which see Chaetopoda.
The following is the main outline of the classification that is adopted in the present article.
Gunther, " On the Structure and Affinities of Mnestra parasites Krohn; with a revision of the Classification of the Cladonemidae," Mitt.
Ti Recently, Warmingi (1909: 136), assisted by VahI, has, odified his earlier classification, and adopted the following: fl A.
When a district like England is divided into edaphic areas, a general classification such as the following may be obtained:
It is a plain, straightforward description of the globe, and of the various phenomena of the surface, dealing only with definitely ascertained facts in the natural order of their relationships, but avoiding any systematic classification or even definitions of terms.
The fundamental form-elements may be reduced to the six proposed by Professor Penck as the basis of his double system of classification by form and origin.'
The terms employed, especially for the subdivisions, cannot be easily translated into other languages, and the English equivalents in the following table are only put forward tentatively Richthofen'S Classification Of Mountains I.
The resulting " classification is based on the examination, mostly autoptic, of a far greater number of characters than any that had preceded it; moreover, they were chosen in a different way, discernment being exercised in sifting and weighing them, so as to determine, so far as possible, the relative value of each, according as that value may vary in different groups, and not to produce a mere mechanical ` key ' after the fashion become of late years so common " (Newton's Dictionary of Birds, Introduction, p. 103).
This method of classification, though formally accurate, has slight value in the exact sciences, partly because at every step one of the two groups is merely negatively characterized and therefore incapable of real subdivision; it is useful, however, in setting forth clearly the gradual descent from the most inclusive genus (summum genus) through species to the lowest class (infima species), which is divisible only into individual persons or things.
If our knowledge of the life-histories of these organisms were perfect, their polymorphism would present no difficulties to classification; but unfortunately this is far from being the case.
Some account of the history of plant classification and the development of a natural system in which an attempt is made to show the actual relationships of plants, is given in the article BOTANY.
Hence both polyp and medusa present characters for classification, and a given species, genus or other taxonomic category may be defined by polyp-characters or medusa-characters or by both combined.
The evidence against this view may be classed under two heads: first, comparative evidence; hydroids very different in their structural characters and widely separate in the systematic classification of these organisms may produce medusae very similar, at least so far as the essential features of medusan organization are concerned; on the other hydroids closely allied, perhaps almost indistinguishable, may produce gonophores in the one case, medusae in the other; for example, Hydractinia (gonophores) and Podocoryne (medusae), Tubularia (gonophores) and Ectopleura (medusae), Coryne (gonophores) and Syncoryne (medusae),-and so on.
While the forms of the sea-bed are not yet sufficiently well known to admit of exact classification, they are recognized to be as a rule distinct from the forms of the land, and the importance Submarine of using a distinctive terminology is felt.
The geographers who have hitherto given most attention to the forms of the land have been trained as geologists, and consequently there is a general tendency to make origin or structure the basis of classification rather than form alone.
The following tables, showing the growth of the largest towns in France, are drawn up on the basis of the fourth classification, which is used throughout this work in the articles on French towns, except where otherwise stated.
Some clue to this enigma might be found by asking a lot of questions.
In 18J5, however, Owen included under Lamarck's term Radiaria the Echinodermata, Anthozoa, Acalepha and Hydrozoa, while Agassiz also clung to the term Radiata as including Echinodermata, Acalepha and Polypi, regarding their separation into Coelenterata and Echinodermata as "an exaggeration of their anatomical differences" (Essay on Classification, London, 1859).
The classification into epithelial organs, connective tissues, and the more specialized muscle and nerve, was largely due to him; and he proved the presence of neuroglia in the brain and spinal cord, discovered crystalline haematoidine, and made out the structure of the umbilical cord.
The vice of the book is excessive classification of bodily faculties, and over-subtlety in the discrimination of diseases.
We may often distinguish between primary symptoms and secondary or subordinate symptoms, but for the purposes of classification in an article of this scope we shall only attempt to group the various cases under the more obvious signs of disease exhibited.
CLAssIFICATIoN o~ PLANTS