CHAPTER XXI.

THE CLASSIFICATION OF FISHES.

Taxonomy.--Defects in Taxonomy.--Analogy and Homology.--Coues on Classification.--Species as Twigs of a Genealogical Tree.--Nomenclature.--The Conception of Genus and Species.--The Trunkfishes.--Trinomial Nomenclature.--Meaning of Species.--Generalization and Specialization.--High and Low Forms.--The Problem of the Highest Fishes. 367