involved had not been cleared up by the discovery of Murchison's errors in stratigraphy, Sedgwick proposed a compromise, according to which the strata from the Bala limestone to the base of the Wenlock were to take the name of Cambro-Silurian; while that of Silurian should be reserved for the Wenlock and Ludlow beds, and for those below the Bala the name of Cambrian should be retained. The Festiniog group (including what were subsequently named the Lingula-flags and the Tremadoc slates) would thus be Upper instead of Middle Cambrian, the original Upper Cambrian being henceforth Cambro-Silurian; it being understood that, wherever the dividing line might be drawn, all the groups above it should be called Cambro-Silurian, and all those below it Cambrian. This compromise was rejected by Murchison, who in the map accompanying the first edition of his Siluria, in 1854, extended the Lower Silurian color so as to include all but the lowest division of the Cambrian; viz., the Bangor group. When, however, the relations of Upper Cambrian and Silurian were made known by the discoveries of Sedgwick and the Government surveyors, this compromise was seen to be uncalled for, and was withdrawn in 1854 by Sedgwick, who re-claimed the name of Upper Cambrian for his Bala group.

In June, 1843, Sedgwick proposed that the whole of the fossiliferous rocks below the horizon of the Wenlock should be designated Protozoic, and on the 29th of November, 1843. presented to the Geological Society an elaborate paper on the Older Paleozoic (Protozoic) Rocks of North Wales, with a colored geological map. This paper, which embodied the results of the researches of Sedgwick and Salter, was not, however published at length, but an abstract of it was prepared by Mr. Warburton, then president of the society, with a reduced copy of the map. [Proc. Geol. Soc. IV, 212 and 251-268; also Geol. Jour. I, 5-22.] In this map of Sedgwick's three divisions were established, viz., the hypozoic crystalline schists of Caernarvonshire, the "Protozoic," and the "Silurian." On the legend of the reduced map, as published by the Geological Society, these latter names were altered so as read "Lower Silurian (Protozoic)" and "Upper Silurian." These changes, in conformity with the nomenclature of Murchison, were, it is unnecessary to say, made without the knowledge of Sedgwick, who did not inspect the reduced and altered map until it was appealed to as an evidence that he had abandoned his former ground, and had recognized the equivalency

of the whole of his Cambrian with the Lower Silurian of Murchison. The reader will sympathize with the indignation with which Sedgwick declares that his map was "most unwarrantably tampered with," and will, moreover, learn with surprise, that an inspection of the proof-sheets of Warburton's abstract of Sedgwick's paper was refused him, notwithstanding his repeated solicitations. The story of all this, and finally of the refusal to print in the pages of the Geological Journal the reclamations of the venerable and aggrieved author, make altogether a painful chapter, which will be found in the Philos. Magazine, for 1854 [IV, viii, pp. 301-317, 359-370, and 483-506] and more fully in the Synopsis of British Paleozoic Rocks, which forms the introduction to McCoy's British Paleozoic Fossils.

In connection with this history it may be mentioned that in March, 1845, Sedgwick presented to the Geological Society a paper on the Comparative Classification of the Fossiliferous Rocks of North Wales and those of Cumberland, Westmoreland, and Lancashire; which appears also in abstract in the same volume of the Geological Journal that contains the abstract of the essay and the map just referred to. [I, 442.] That this abstract also is made by another than the author is evident from such an expression as "the author's opinion seems to be grounded on the following facts, etc.," (p. 448) and from the manner in which the te.ms Lower and Upper Silurian are applied to certain fossiliferous rocks in Cumberland. Yet the words of this abstract are quoted with emphasis in Siluria [1st ed., 147] as if they were Sedgwick's own language recognizing Murchison's Silurian nomenclature.

II. MIDDLE AND LOWER CAMBRIAN.

Investigations in continental Europe were, meanwhile, prepar ing the way for a new chapter in the history of the lower paleozoic rocks. A series of sedimentary beds in Sweden and Norway had long been known to abound in singular petrifications, some of which had been examined by Linnaeus, who gave to them the name of Entomolithi. They were also studied and described by Wahlenberg and by Brongniart, the latter of whom, from two varieties of the Entomolithus paradoxus, Linn, established in 1822 two genera, Paradoxides and Agnostus. In 1826 appeared a memoir by Dalman on the Palade or so-called Trilo

bites; which was followed, in 1828, by his classic work on the same subject. [Uber de Palaeaden oder so-genanten Trilobiten, 4to. with six plates, Leipsic.] In these works were described and figured, among many others, two genera-Olenus, which included. Paradoxides, Brongn, and Battus, including Agnostus of the same author. Meanwhile, Hisinger was carefully studying the strata in which these trilobites were found in Gothland, and in the same year (1828) published in his Anteckningar, or Notes on the Physical and Geognostical Structure of Norway and Sweden, a colored geological map and section of these rocks as they occur in the county of Skaraborg; where three small circumscribed areas of nearly horizontal fossiliferous strata are shown to rest upon a floor of old crystalline rocks, in some parts granitic and in others gneissic in character. The section and map, as given by Hisinger, show the succession in the principal area to be as follows, in ascending order: 1. granite or gneiss; 2. sandstone; 3. alum-slates; 5. orthoceratite-limestones; 4. clayslates. By a curious oversight the colors on the legend are wrongly arranged and wrongly numbered, as above; for in the map and section it is made clear that the succession is that just given, and that the clay-slates (4), instead of being below, are above the orthoceratite-limestones (5).

In 1837, Hisinger published his great work on the organic remains of Sweden, entitled Lethon Suecica [4to. with forty-two plates.] In this he gives a tabular view, in descending order, of the rock-formations, and of the various genera and species described. The rocks of the areas just noticed appear in his fourth or lowest division, under the head of Formationes transitionis, and are divided as follows:

a. Strata calcarea recentiora Gottlandiæ.

b. Strata schisti argillacei.

c. Strata schisti aluminaris.

d. Strata calcarea antiquiora.

e. Strata saxi arenacei.

The succession thus given was however erroneous, and probably, like the mistake in the legend of the same author's map just mentioned, the result of inadvertence, the true position of the alum-slates (c) being between the older limestone (d) and the basal sandstone (e). This is shewn both by Hisinger's map of 1828, and by the testimony of subsequent observors. In Murchison's work on the Geology of Russia in Europe, publish

ed in 1845, there is given (page 15 et seq.) an account of his visit to this region in company with Prof. Loven, of Christiania; which, with figures of the sections, is reproduced in the different. editions of Siluria. The hill of Kinnekulle on Lake Wener, is one of the three areas of transition rocks delineated on the map of Hisinger above referred to. Resting upon a flat region of nearly vertical gneissic strata, we have, according to Murchison; 1. a fucoidal sandstone; 2. alum-slates; 3. red orthoceratitelimestone; 4. black graptolitic slates; the whole series being little over 1000 feet in thickness, and capped by erupted greenstone. Above these higher slates there are found in some parts of Gothland, other limestones with orthoceratites, trilobites and corals, the newer limestone strata (a) of Hisinger; the whole overlaid by thin sandstone beds. These higher limestones and sandstones contain the fauna of the Wenlock and Ludlow of England; while the lower limestones and graptolitic slates afford Calymene Blumenbachii, Orthis calligramma, and many other species common to the Bala group of North Wales. The alumslates below these however, contained, according to Hisinger, none of the species then known in British rocks, but in their stead five species of Olenus and two of Battus (Agnostus.)

In 1854, Angelin published his Palaeontologica Scandinavica, part I, Crustacea formationis transitionis, [4to. forty-one plates] in which he divided the series of transition rocks above described by Hisinger into eight parts designated by Roman numerals, counting from the base. Of these I was named Regio Fucoidarum, no organic remains other than fucoids being know therein; while the remaining seven were named from their characteristic genera of trilobites, which were as follows, in ascending order; certain letters being also used to designate the parts: II. (A) Olenus; III. (B) Conocoryphe; IV. (BC) Ceratopyge; V. (C) Asaphus; VI. (D) Trinucleus; VII. (DE) Harpes; VIII. (E) Cryptonymus. In the Regio Olenorum (II) was found also the allied genus Paradoxides. With regard to the characteristic genus of Regio III., the name of Conocoryphe was proposed for it by Corda in 1847, as synonymous with Zenker's name of Conocepha lus (Conocephalites) already appropriated to a genus of insects.

Meanwhile, the similar crustaceans which abound in the transition rocks of Bohemia had been studied and described by Hawle, Corda and Beyrich, when Barrande began his admirable investigations of this ancient fauna and of its stratigraphical re

lations. He soon found that beneath the horizon characterized by fossils of the Bala group (Llandeilo and Caradoc) there existed in Bohemia a series of strata distinguished by a remarkable fauna, entirely distinct from anything known in Great Britain, but closely allied to that of the alum-slates of Scandinavia, corresponding to Regiones II. and III. of Angelin. To this he gave the name of the first or primordial fauna, and to the rocks yielding it that of the Primordial Zone. Resting upon the old gneisses of Bohemia appears a series of crystalline schists designated by Barrande as Etage A, overlaid by a series of sandstones and conglomerates, Etaye B, upon which repose the fossiliferous argillites of the primordial zone or Etage C. The rocks of the Etages A and B were by Barrande regarded as azoic, but in 1861, Fritsch of Prague, after a careful search, discovered in certain thin-bedded sandstones of B, the traces of filled-up ver. tical double tubes; which, according to Salter, [Mem. Geol. Sur. III., 243] are probably the marks of annelides, and are identical with those found in the rocks of the Bangor or Longmynd group in Great Britain; which will be shown to belong to the primordial zone. It is, therefore, probable that the Etage B, which apparently corresponds to the Regio Fucoidarum or basal sandstone of Scandinavia, should itself be included in the primordial zone. It may here be noticed that it is in the crystalline schists of A that Gumbel has found Eozoon Bavaricum. To the Etage C in Bohemia, Barrande assigns a thickness of about 1200 feet, and to this his first fauna is confined, while in the succeeding divisinos he distinguished a second and a third. The second fauna, which characterizes Etage D, corresponds to that of the Bala group; while the third fauna, belonging to the Etages E, F, G and H, is that of the May Hill, Wenlock and Ludlow formations of Great Britain.

'This classification of the ancient Bohemian faunas was first set forth by Barrande in 1846, in his Notice Preliminaire, in which he declared that the first fauna was below the base of the Llandeilo of Murchison, unknown in Great Britain, and, moreover, "new and independent in relation to the two Silurian faunas (his second and third) already established in England." This opinion he reiterated in 1859. These three divisions form in Bohemia an apparently continuous series, and being connected with each other by some common species, Barrande was led to look upon the whole as forming a single stratigraphical system;