78 GENERAL ORNITHOLOGY. 



malia and Aves 001160117617, that every mammal must be more highly organized than every 

 bird. It is difficult to say hovir a mole or a mouse is a more elaborate or more capable creature 

 than a canary-bird, physically or mentally. The relative rank of two groups is determined 

 by balancing the aggregate of their structural characters. In large series, the average of 

 development, not the extremes either way, is taken into account ; so that the lowest members 

 of a higher gi'oup may be below the highest members of the next lower group. The common 

 phrase, " below par,'' or "above par," is most applicable to such oases. 



Machinery of Classlfloation. — The inexperienced student may be glad to be given some 

 explanation of the way in which the taxonomic principles we have discussed are applied, and 

 carried into practical effect in classifying birds. Our machinery for that purpose is our inherit- 

 ance from those naturalists who held very different views from those which touch the evolu- 

 tionary key-note of modem classification. It is clumsy, and does not work weil as a means of 

 expressing the relations we now believe to be sustained by all organisms toward one another ; 

 but it is the best we have. Systematic zoology, or the practice of classification, has failed to 

 keep pace with the principles of the science ; we are greatly in need of some new and sharper 

 " tools of thought," which shall do for zoology what the system of symbols and formulae have 

 done for chemistry. We wcmt some symbolic formMlation of owr knowledge. The invention of 

 a practicable scheme of classification ^nd nomenclature, which should enable us to formulate 

 what we mean by Twdus nigratoriuiS, as a chemist symbolizes by SO4H2 what he understands 

 hydrated sulphuric acid to be, would be an inestimable boon to working naturalists. The 

 mapping out of groups with connecting lines to indicate then- genetic relations, in the form of a 

 " phylum," is a common practice ; but that, like any other pictorial representation of a " fami- 

 ly tree," is not the graphic symbohzation required. The first steps in this direction have been 

 tentatively taken already by the late Mr. A. H. Garrod and others : we already have a mother 

 of the required invention in the necessity of the case, and may hope that the father wDl not be 

 long in coming. 



Under the present system. Birds are called a "Class" of Vertebrates, and are subdivided 

 into "orders," "families," "genera," "species" and "varieties," as already sufficiently indicated. 

 Oroups intermediate to any of these may be recognized ; and if so, are usually distinguished 

 by the prefix sub-. Many other terms are in occasional use, as "tribe," "race," "series," 

 "cohort," "super-family"; but those first mentioned are the best established ones among 

 English-speaking naturalists. Their sequence is fixed, as above, from higher to lower, in 

 relative rank.^ With the exceptions to be presently noted, the names of any groups are 

 arbitrary, at the wiU of the person who founds and designates them. The framer of a geuus, 

 or the desoriber of a species, calls it what he pleases, and the name he gives holds, subject to 

 certain statutory regulations which naturalists generally agree to abide by. The exceptions 

 are the names of families and sub-families, the former commonly being made to end in -idm, the 

 latter in -mce : family Twrdidce ; sub-family Twrdmm. This is a great convenience, since we 

 always know the rank intended to be noted by these forms. The names of groups higher than 

 species are almost invariaj)ly single words ; as, order Passeres ; but sometimes, especially in 

 cases of intennediate groups, two words are used, one qualifying the other; as, sub-order 

 Passeres Acromyodi, or osoine Passeres. A generic or sub-generic name is always a single 

 word ; these, and the names of all higher groups, invariably begin with a capital letter. 



Until quite recently, the scientific name of any^ individual bird almost invariably consisted 

 of two terms, generic and specific, — the name of the genus, followed by the name of the 



» The expression "higher group," in the sense of relative rank In the taxonomic scale, will of course be dis- 

 tinguished ftom the same expression when applied to the relative rank in the scale of organization of the objects 

 classified. An order of birds is a " higher group " than a family of birds, In the former sense, but no higher than 

 an order of worms, in the latter sense. 



