WE have excellent examples of the advantageous use of this maxim in Linnæus's reform of botanical nomenclature. His innovations were very extensive, but they were still moderated as much as possible, and connected in many ways with the names of plants then in use. He has himself given several rules of nomenclature, which tend to establish this connexion of the {342} old and new in a reform. Thus he says, 'Generic names which are current, and are not accompanied with harm to botany, should be tolerated[59\4].' 'A passable generic name is not to be changed for another, though more apt[60\4]'. 'New generic names are not to be framed so long as passable synonyms are at hand[61\4].' 'A generic name of one genus, except it be superfluous, is not to be transferred to another genus, though it suit the other better[62\4].' 'If a received genus requires to be divided into several, the name which before included the whole, shall be applied to the most common and familiar kind[63\4].' And though he rejects all _generic_ names which have not a Greek or Latin root[64\4], he is willing to make an exception in favour of those which from their form might be supposed to have such a root, though they are really borrowed from other languages, as _Thea_, which is the Greek for goddess; _Coffea_, which might seem to come from a Greek word denoting silence (κωφός); _Cheiranthus_, which appears to mean hand-flower, but is really derived from the Arabic _Keiri_: and many others. [Note 59\4: _Philosophia Botanica_, Art. 242.] [Note 60\4: Art. 246.] [Note 61\4: Art. 247.] [Note 62\4: Art. 249.] [Note 63\4: Art. 249.] [Note 64\4: Art. 232.] As we have already said, the attempt at a reformation of the nomenclature of Mineralogy made by Professor Mohs will probably not produce any permanent effect, on this account amongst others, that it has not been conducted in this temperate mode; the innovations bear too large a proportion to the whole of the names, and contain too little to remind us of the known appellations. Yet in some respects Professor Mohs has acted upon this maxim. Thus he has called one of his classes _Spar_, because _Felspar_ belongs to it. I shall venture to offer a few suggestions on this subject of Mineralogical Nomenclature.