~~ 
Parr Il. Secor. ii.§2] SILURIAN, 689 
(Limestone usually somewhat bituminous, with partings of reddish-yellow 
| and brown very bituminous marl (Beyrichia complicata, Asaphus 
acuminatus, Orthis calligramma, Leptena sericea, &ec.). 
Orthoceratite limestone (Vaginaten-Kalk) and marl bands, 15 to 40 feet 
{ thick (Monticulipora petropolitana, Eehinospherites aurantium, Asaphus 
expansus, Orthis calligramma, Orthoceras vaginatum, &c.). 
Limestone, full of glauconite grains, especially towards the bottem (Orthis 
| calligramma, O. extensa, abundant fragments of Illenus and Azaphus, 
\ &e.). 
(Glauconite sand (6 feet), with numerous foraminifera in the glauconite 
grains (Panderella, Cymbulia, Tiedemannia, &c.) and the “ Conodonts ” 
: of Pander. 
£09 |Alum-slate (10 feet), highly carbonaceous, with pyrite-nodules and 
5 ~ abundant graptolites (Dictyonema Hisingeri, Obolus, &c.). 
aeunte sandstone (120 feet), yellow to white, with (in the upper part) 
Llandeilo, 
Areni 
abundant shells of Obolus Apollinis (“‘ Ungulites ” of Pander). 
Blue Clay, with sandstone bands, sparingly fossiliferous; bored at Revel 
\ to a depth of 800 feet without its bottom being reached. 
Bohemia.'—In the centre and south of Europe by far the most 
- important Silurian area is the basin of Bohemia, so admirably worked 
out by M. Barrande, wherein the formations are grouped as in the sub- 
joined table : 
(Etage H Shales with coaly layers and beds of quartzite 
(Phacops fecundus, Tentaculites elegans), with 
| species of Leptena, Orthoceras, Lituites, Goniatites, 
&e. . : 2 : : : : ‘ - 850 ft. 
| G Argillaceous limestones with chert, shales, and 
calcareous nodules . é ; : : 2000 <: 
Numerous trilobites of the genera Dalmanites, 
Bronteus, Phacops, Proétus, Harpes, and Caly- 
mene; Atrypa reticularis, Pentamerus linguifer. 
F Pale and dark limestone with chert. Harpes, 
; Lichas, Phacops, Atrypa reticularis, Pentamerus 
galeatus, Favosites gothlandica, F. fibrosa, Tenta- 
| culites. 
E Shales with calcareous nodules, and shales resting 
on sheets of igneous rock (800 ft.) : - 400-900 ,, 
A very rich Upper Silurian fauna, abundant cepha- 
lopods, trilobites, &c.; Halysites catenularia, 
\ graptolites in many species. 
: | » D Yellow, grey, and black shales, with quartzite and 
-—————so 
3rd Fauna, 
Upper Silurian. 
58 3 conglomerate at base. : : 3 ‘ - 5000 ,, 
e5(& 5 Abundant trilobites of genera Trinucleus, Ogygia, 
a ay Asaphus, Illenus, Remopleurides, &e. 
= \e .¢ ,, C Shales or “schists,” sometimes with porphyries 
2/lg¢ and conglomerates. : d ; . 900-1200 ,, 
= S83 Paradoxides, Ellipsocephalus, Agnostus, and other 
s 5 = genera of trilobites referred to above (ante, p. 659). 
Ss ) Bis. aa aR a 
S f be Aj Schiats wholly unfossiliferous restiug on gneiss. 
<a 39 
The lower two étages (A, B) correspond probably to some of the older 
parts of the British Cambrian series, and perhaps in part to still older 
rocks. Bitage C, or the Primordial Zone, is the equivalent of the Upper 
Cambrian rocks of Wales, possibly also partly of the Arenig series. 
- Btage D, subdivided into five groups (d1, d2, d3, d4, and d5), appears to 
be, on the whole, representative of the Lower Silurian formations of the 
British area, though it is impossible to make the minor subdivisions in 
1 See Barrande’s magnificent work, “Systeme Silurien de la Bohéme.” 
ee 2°¥ 

