“Ignorato genere proprio, nulla descriptio, quamvis accurate tradita certum demonstret; sed plerumque fa11at.”-Cæsalp. apud Linn., SystNat., xii, 1, 13.

In the first part of this essay I endeavored to show the confusion which resulted from the application of the law of priority to the names employed in the early development of our science by persons who had no idea corresponding to the law which has since been formulated. We will now attempt to discuss the second great fallacy in the exegesis of the writings of the founders of the science ; the selection on principles, more or less arbitrary, but always opinionative, of generic types, when these have not been explicitly mentioned by the author.