

systems, 
Parr IL Sxcr. ii.§2.] SILURIAN. 
ridge of the north-west of France. According to recent researches, ! 
order of succession in Brittany (Ille-et-Vilaine) is as under : 
White limestone of Erbray (Calymene Blumenbachii, Harpes venulosus). 
Ampelitic or carbonaceous limestone of Briasse. 
Sandy and ferruginous nodules of Martigné-Ferchaud, Thourie, &c. (Cardiola 
interrupta, Monograptus (Graptolithus) priodon). 
Carbonaceous (ampelitic) shales of Poligné, and phthanites of Anjou (Mono- 
graptus (Graptolithus) colonus). 
Slates of Riadan (T'rinucleus). 
Sandstones (May, Thourie, Bas Pont, Saint-Germain de la Bouexiere, &c.), con- 
taining Trinucleus Goldfusst, Calymene Bayani, Orthis redux, O. budlei- 
ghensis, O. pulvinata, ©. valpyana, O. Berthosi, Nucleospira Vicaryt, Lingula 
Morierei, Pseudarca typa, Diplograpsus Baylei ; probably equivalent to the 
British Caradoc group. 
Slates of La Couyére (Orthis Berthosi). 
Nodular shales of Guichen, &e. (Calymene Tristani, Placoparia Tourneminei, 
Acidaspis Buchit). 
Slates of Angers (Ogygia Desmarest?). 
Shales of Laillé and Sion (Placoparia Zippet, Hyolithes cinctus). 
Armorican sandstone (Gres Armoricain), possibly the base of the Lower Silurian 
(lowest Llandeilo or Arenig) or second fauna of Barrande (Asaphus armori- 
canus, Lingula Lesueurt, L. Hawket, L. Salteri, Dinobolus Brimonti, Lyro- 
desma armoricana, annelides). 
Red shales and conglomerates without fossils, 
In Germany Silurian rocks appear in a few detached areay, 
Among the Alps the band of ancient sedimentary rocks wh 
flanking the crystalline masses of the central chain, has been termed 
““oreywacke zone,’ has in recent years been ascertained to contain 
representatives of the Silurian, Devonian, Carboniferous, and Permian 
In the eastern Alps a belt of clay-slate and greywacke, with 
limestone, dolomite, magnesite, ankerite, and siderite runs from Kitzbiihel 
691 
the 
but 
present a great contrast to those of Bohemia in their comparatively 
unfossiliferous character, and the absence of any one continuous suc- 
cession of the whole Silurian system. They occur in the Thuringer 
Wald, where a series of fucoidal-schists (perhaps Cambrian) passes up 
into slates, greywackes, &c., with Lingula, Discina, Calymene, numerous 
graptolites, and other fossils, These strata (from 1600 to 2000 
thick) may represent the Lower Silurian groups. 
-some graptolitic alum-slates (Monograptus, Diplograpius), shales, flinty 
slates,and limestones (Favosites gothlandica, Cardiola interrupta, Tentacu 
acuarius, &c.), which no doubt represent the Upper Silurian groups, 
pass into the base of the Devonian system.2. Among the Harz Mountains 
certain greywackes and shales containing land-plants (lycopods, &c.), 
trilobites (Dalmanites, &c.), graptolites, &c., are regarded as of inter- 
mediate age between true Upper Silurian and Lower Devonian rocks.® 
In the western half of the Spanish peninsula Silurian rocks are found 
flanking the older schists and crystalline masses, and spreading ov 
vast area of the table-land. They appear to belong chiefly if not wh 
to the lower division of the system, and they include representatives of 
Barrande’s primordial zone, containing 19 species of organisms of which 
nine are primordial trilobites. 
feet 
They are covered by 
lites 
and 
er a 
olly 
ich, 
the 
1 De Tromelin et Lebesconte, Bull. Soc. Géol. France, 1876, p. 585. Assoc. Frang 
2 Richter, Zeztsch. Deutsch. Geol, Gesell. xxi. p. 359; xxvii. p- 261, 9 
3 Lossen, op. cit, xx. p. 216; xxi. p. 284; xxix. 612. Y.2 
1875. Bull. Soc. Linn. Normandie, 1877, p. 5. See also Dalimier, “ Stratigraphie des 
Terrains primaires dans la presqwile de Cotentin,”’ Paris, 1861 ; Bull. Soc. Géol. France. 
1862, p. 907; De Lapparent, Bull. Soc. Géol. France, 1877, p. 569. 
