Part IIL Sect. ii. §2.] JURASSIC. 799 
Clays with Ammonites ornatus. 
Shales with A. macrocephalus. 
= -. (Upper 4 Cornbrash with Avicula echinata, Amm. posterus. 
S65 | Shales with Ostrea Knorri, Amm. ferrugineus. 
jaa) Sp | Zone of Amm. Parkinsoni. ee 
i . Coronaten-Schichten, clays wit elemnites giganteus, Amm. 
: 3 S| Middle { Humphriesianus, Amm. Braikenridgi. 
3S 5 Shales, sandstones, and ironstones, with Inoceramus polyplocus, 
5 | Lower Amm. Murchisone. 
= Clays and shales with Amm. opalinus. 
Grey marls with Ammonites jurensis. 
Bituminous shales (Posidonien-schiefer) with Amm, lythensis, 
A. communis, A. bifrons, Posidonia Bronni. 
Clays with Amm. spinatus. 
Middle | Marls and limestones with Amm. capricornus, A. Daveet. 
Dark clays and ferruginous marls with A. brevispina. 
Clays with Amm. planicosta, A. raricostatus. 
Blue grey clays with A. Bucklandi (Arietenschichten). 
Dark clays with A. angulatus. 
Dark clays and sandy layers with A. planorbis ( psilonotus), 

- ( Upper 
8) 
1a 
Lower or Black 
Jura (L 
Lower 

In lithological character the German Lias presents many points of re- 
semblance to that of England. Some of the shales in the upper division 
are so bituminous as to be workable for mineral oil. With the general 
succession of organisms also, so well worked out by Oppel, Quenstedt, and 
others, the English has been found to agree closely. The Dogger or 
Brown Jura represents the Lower Oolite of England and the Etage 
Bajocien and Bathonien of France. Its lower division consists mainly 
of dark clays and shales, passing up in Swabia into brown and yellow 
‘sandstones with ooliticironstone. The central group in northern Germany 
differs from the corresponding beds in England, France, and southern 
Germany by the great preponderance of dark clays and ironstone nodules. 
The upper group consists essentially of clays and shales with bands of 
oolitic ironstone, thus presenting a great difference to the massive cal- 
careous formation on the same platform in England and France. The 
Malm, or Upper (white) Jura corresponds to the Middle and Upper 
Oolites of England, from the Kellaways rock upwards, with the equivalent 
formations in France. It is upwards of 1000 feet thick, and derives its 
name from the white or light colour of its rocks contrasted with the dark 
tints of the Jurassic strata below. It consists mainly of white limestones 
in many varieties; other materials are dolomite and calcareous marl. Its 
lower (Oxford) group is essentially calcareous, with no lithological equi- 
valent of the true Oxford clay, but it contains some of the fossils which 
occur in that clay, e.g. Ammonites cordatus and Gryphza dilatata. The 
massive limestones with Cidaris florigemma are doubtless the equivalents 
of the Corallian. The Kimmeridge group presents at its base beds equi- 
valent to the Astartian zone of France (Astarte supracorallina, Natica 
globosa, &c.), with such an abundance and variety of the gasteropod genus 
Nevinea that the beds have been named the ‘“ Nerineen-Schichten.” 
Above these come beds with Pteroceras Oceani, marking the central zone 
of the Kimmeridge formation. Higher still lie compact and oolitic lime- 
stones with Hxogyra virgula, representing the upper or Virgulian stage. 
At the top come limestones and marly clays with Ammonites giganteus, 
which indicate the Portland formation. The most important member of 
the German Kimmeridge series is undoubtedly the limestone long 
quarried for lithographic stone at Solenhofen near Munich. Its excessive 
