As greater numbers of species have become known the earlier genera have undergone subdivision until in the modern systems almost any structural character not subject to intergradation and capable of exact definition is held to distinguish a genus. As the views of these characters are undergoing constant change, and as different writers look upon them from different points of view, or with different ideas of convenience, we have constant changes in the boundaries of genera. This brings constant changes in the scientific names, although the same specific name should be used whatever the generic name to which it may be attached. We may illustrate these changes and the burden of synonymy as well by a concrete example. =The Trunkfishes.=--The horned trunkfish, or cuckold, of the West Indies was first recorded by Lister in 1686, in the descriptive phrase above quoted. Artedi, in 1738, recognized that it belonged with other trunkfishes in a group he called _Ostracion_. This, to be strictly classic, he should have written _Ostracium_, but he preferred a partly Greek form to the Latin one. In the Nagg's Head Inn in London, Artedi saw a trunkfish he thought different, having two spines under the tail, while Lister's figure seemed to show one spine above. This Nagg's Head specimen Artedi called "_Ostracion triangulatus duobus aculeis in fronte et totidem in imo ventre subcaudalesque binis_." Next came Linnæus, 1758, who named Lister's figure and the species it represented, _Ostracion tricornis_, which should in strictness have been _Ostracion tricorne_, as ~ostrakion~, a little box, is a neuter diminutive. The Nagg's Head fish he named _Ostracion quadricornis_. The right name now is _Ostracion tricornis_, because the name _tricornis_ stands first on the page in Linnæus' work, but _Ostracion quadricornis_ has been more often used by subsequent authors because it is more truthful as a descriptive phrase. In 1798, Lacépède changed the name of Lister's fish to _Ostracion listeri_, a needless alteration which could only make confusion. [Illustration: FIG. 240.--Horned Trunkfish, _Ostracion cornutum_ Linnæus. East Indies. (After Bleeker.)]