to which it refers has been changed from its original character through devitrification.

Mica-Syenites at Rothschonberg.-Two dykes of mica-syenite cut the phyllite formation near Rothschönberg, Saxony, producing in the neighboring rocks contact metamorphism. One of the dykes weathers spheroidally, and in the kernels of the spheroids fresh material for study was afforded Henderson, who found the rock to be composed of orthoclase, plagioclase, quartz, biotite, apatite and several accessory components. The feldspar and quartz both occur in grains and in crystals, the biotite in flakes. An analysis of the rock gave the figures below (I).

The second occurrence differs little from the first. Muscovite is present as well as biotite, otherwise the two rocks are practically alike in mineral composition. Its chemical composition is shown in (II).

SiO, AO, Fe,O, CaO MgO K2O Na2O H2O CO, S

2

Total

I. 61.40 16.66 7.46 2.08 3.65 2.93 4.75 .76 1.54 .20-101.43 II. 57.63 16.47 5.37 5.25 4.44 3.12 5.15 .45 2.14 .95-100.97 The structure of both rocks was panidiomorphic, although the development of secondary quartz renders them now hypidiomorphic. They are syenitic aplites. In the neighboring phyllites new biotite has been abundantly developed and hornblende has been produced in some quantity. The free silica which is abundant in the unaltered phyllites has become combined with metallic elements in the altered forms. While the percentage of silica in specimens taken at 2 meters and 11 meters from the contact and at the contact is the same, the free quartz in the first is 43.38 per cent of the rock's mass, in the second 38.94 per cent and in the third 34.06 per cent.

GEOLOGY AND PALEONTOLOGY.

Cambrian Rocks of Pennsylvania.-During the years 1892 and '93, Mr. Walcott made an examination of the rocks of Cambrian southeastern Pennsylvania for the purpose of determining whether the lower quartzites with their superjacent limestones were of the same geologic age, in the areas included between the Potomac and Susquehanna and the Delaware and Susquehanna Rivers. The results of his work are published in bulletin form by the U. S. Geological Survey. 5 Zeits. d. geol. Ges., XLVII, p. 534.

Mr. Walcott began the investigation in York County, where he determined the stratigraphic position of the Chickies quartzites and the York shales which are subjacent to the Lancaster (York Frazer) limestone. Paleontologic evidence shows them to be of Lower Cambrian age. The fauna of the main body of the limestone of York County, as shown by collections from three separate localities, is Cambrian. These localities indicate respectively, an Upper Olenellus zone, a horizon between the Lower and Middle Cambrian, and a lower horizon of the Middle Cambrian.

The discovery of Lower Cambrian fossils in the compressed syncline of limestone in Lancaster County, south of Columbia, indicates that the limestone on the west side of the river is of the same geologic age, and that the shales and schists beneath it are of Lower Cambrian age.

Mr. Walcott states that in York County there is no sedimentary rock other than the mesozoic new red sandstone-of later age than the Cambrian, unless it be the Peach Bottom slates and chlorite-schists of the southeastern corner of the country. He also thinks it probable from the closely related structure of Lancaster County that all the Lancaster limestones will fall within the Cambrian, unless it be some portions of the upper series, which may pass into the Ordovician. He applies this generalization to the entire extension of this series of limestone northeastward to the Delaware.

All of the quartzites that have been referred to the Potsdam necessarily fall into the Lower Cambrian, as they are beneath the limestones. The South Mountain chain, as stated by Professor Lesley and Dr. Frazer, consists of two groups of rocks, a quartzite and an orthofelsite series, the latter being considered the superior series. Mr. Walcott's investigations lead him to a different interpretation of the geologic structure of the mountain and the relations of the rocks composing it. He finds that the "orthofelsite" is in reality the lower series, and that the complicated structure of the mountain arises "partly from folding, but more largely from the westward thrusts of masses of strata along the lines of fault of a low hade. This westward thrusting on the fault plane, complicated by previous folding of the strata, leaves masses of the subjacent, pre-Paleozoic rocks resting in various places on different members of the Lower Cambrian series, and also appears to interbed the quartzites and schists of the Cambrian in the schists, eruptives, etc., of the Algonkian."

The following are the concluding remarks in the section on Correlation:

"The discovery of the Olenellus or Lower Cambrian fauna in the Reading sandstone practically completes the correlation of the South Mountain, Chickies and Reading quartzites, and establishes the correctness of the early correlations of McClure, Eaton, Emmons and Rogers. They all considered the basal quartzite as the same formation from Vermont to Tennessee; and the discoveries of recent years have proved that the basal sandstones of Alabama, Tennessee and Virginia (Chilhowee quartzite); Maryland, Pennsylvania and New Jersey (Reading quartzite); New York and Vermont (Bennington quartzite), were all deposited in Lower Cambrian time, and that they contain the characteristic Olenellus fauna throughout their geographic distribution. The superjacent limestones carry the Olenellus fauna in their lower portions in northern and southern Vermont, eastern New York, New Jersey and Pennsylvania. To the south of Pennsylvania the lower portions of the limestones appear to be represented by shales, and the Upper and Middle Cambrian faunas are found in the lower half of the Knox dolomite series of Tennessee, and they will probably be discovered in the same series in Virginia and Maryland when a thorough. search is made for them. The same may be predicted, but with less assurance, for the northern belt of limestone crossing Pennsylvania into New Jersey as the limestones between the Olenellus zone and the Trenton zone represent the intervals of the Middle and Upper Cambrian and the Lower Ordovician, or the Calciferous and Chazy zones of the New York section."

Nothing was discovered upon which could be based a line of demarcation between the Cambrian and Ordovician linestones in the series. under discussion. The division is still an open question to be decided by future revelations of lithologic and paleontologic characters. (Bull. U. S. Geol. Surv., No. 134, Washington, 1896.)

Structure of Uintacrinus.-Since Uintacrinus was first made known by Grinnell, some twenty years ago, little notice has been taken of the form. Of late, however, special interest in the type has been revived, and the form comes in for consideration in several important articles. Among them are W. B. Clark's review of the Mesozoic Echinodermata of the United States', in which all known material is described, and the structure amply illustrated by figures. Shortly after Williston and Hill' gave some "Notes on Uintacrinus socialis" as found in Kansas. Still more recently Bather has gone over all the 'U. S. Geol. Sur., Bull. 97, pp. 21-24, 1893.

2 Kansas Univ. Quarterly, Vol. III, pp. 19–21, 1894. Proc. Zool. Soc., London, 1895, pp. 974-1004, 1896.

available data, and has made the type of Uintacrinus the subject of a a special morphological study. In this treatment the previous work is briefly referred to; but some of it receives criticism that it does not appear to deserve, particularly since the foundation of most of the adverse comments lies not in any material error in the work referred to, but in what is manifestly a clear misinterpretation or hasty perusal of that work. It is to certain of these points in the structure of the form that attention is directed in the present note. In making the correction, however, it is not with the idea of reflecting on Mr. Bather's paper as a whole, for it is one of the most excellent contributions to echinoderm morphology that has yet appeared. The original figures in question from Bulletin 97 of the U. S. Geological Survey are herewith reproduced (Plate XV) in order to make more intelligible the exact points under consideration.

In the memoir mentioned considerable space is occupied in criticising a recent account of the species; but most, if not all of the objections urged against Doctor Clark's work, are certainly more imaginary than real. Professor Clark's figures come in for special condemnation as violating the fundamental law of the alternation of the pinnules. As a matter of fact his plate which is reproduced in the Proceedings as Plate LVI, to point out the alleged errors, not only shows that the accompanying statements are not true, but that in all three figures there is strict alternation of the pinnules in every case.

The general law in the pinnulation of the genus Mr. Bather states as follows: IIBr, none, IIBr, outer, IIBr, none, IIBr, inner, IIBr, outer, IIBr, none, IIBr, inner, IIBr, outer, IIBr, none. Two of his ten specimens differed from this general rule: one showing IIBr, inner, IIBr, none, IIBr, outer, IIBr, inner; and the other IIBr, none, IIBr, outer, IIB, inner, II Br, none, IIBr, outer. He makes out the formula for the Clark figure la to be IIBr, outer, IIBr, none, IIBr, outer. The real formula for this is IIBr, outer, IIBr, inner, IIBr, outer, IIBr, inner, IIBr, outer. This appears clearly indicated in the figure, and Mr. Bather's statements that IIBr, has no pinnule is certainly a typographical error, for it cannot be that he mistook the rough, broken and highly raised edge of the brachial row of plates, with its deep shadow, for a suture line connecting with the first inside pinnule. The figure is of a somewhat crushed and distorted specimen, and the perspective is, perhaps, not as good as it might be. Whether or not it is the same as that figured by Meek (Bather's figure 2) is not known; but if the two are the same, the difference in the sketches are not very great nor radical, and certainly not as contradictory as Mr. Bather would have