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which accompanies Lyman's protest, I am at present of opinion that the needs of geologists are better served by Newark than by New Red, Jurassic, Jurassico-Triassic, or Rhætic.

It may be assumed that there is no difference of opinion as to the propriety of giving local geographic names to the minor stratigraphic units. Such is the modern practice of most geological surveys, and it has the sanction of the International Congress of Geologists. Lyman, too, in the paper cited, introduces Pottstown shales, Lansdale shales, Norristown shales, Perkasie shales and Gwynedd shales as the names of newly recognized formations in eastern Pennsylvania and the contiguous parts of New Jersey, deriving the distinctive word in each case from the local geography. The stratigraphic units thus distinguished are all parts of the larger unit to which Redfield applied the local geographic name "Newark."

But Lyman protests against the use of the local name for the larger unit. It is not entirely clear to me whether he holds that the larger unit should have no name, or that it should not have a local name, or only that it should not receive the particular local name; and I therefore find it easier to state the basis of my own opinion than to discuss his view.

1. In my opinion the larger unit should have an individual name.—In the nomenclature of stratigraphy, as in language generally, it is advantageous to avoid paraphrases by giving a short name to every concept which needs frequently to be expressed. That for which Redfield proposed the name "Newark group"^[1] is a stratigraphic integer, so definitely limited in nature that its individuality has been recognized in the literature of a half century. In the paper just referred to it is distinctly recognized by Lyman, who calls it in one place "the older Mesozoic rocks of New Jersey," and elsewhere "the older Mesozoic," "the so-called New Red," "the New Red beds," "the New Red." Each of these terms is used as a name rather than as a description; even the long phrase "the older Mesozoic rocks of New Jersey" is not a definition, for it is made to cover rocks, for example, the