It is only within quite recent times that anatomists have realized that the comparisons with which they help out their descriptions of parts of the brain are likely to become fixed as the names of the parts. Even in the beginning of this century—indeed the custom has not altogether ceased even yet—they quoted the illustrations used by their predecessors, to replace them at once by new ones, if any, more apposite, occurred to them, without recognising the risk of confusion likely to arise from the Multiplicity of names. There is a curious alternation between the use of the simile as an unalterable symbol and as an aid to description. In other words, we strike in quite recent anatomical strata upon stages in word-formation which are deep down in the history of other sciences. Galen converted illustrations into cognomens for most of the bones, muscles, and other parts of the body, but the anatomists of the 17th and 18th centuries, when writing of the parts of the brain, considered it as immaterial whether or not they used the same symbols or illustrations as their predecessors; they did not regard its terminology as in any degree fixed, and if a new illustration occurred to them which conveyed a better idea of the form of the part than any as yet current, by all means let posterity make use of it!.