Parr IIL. Sect, ii. §2.] JURASSIC. 797 
vary from the English type as they are traced to the south and east. 
The following table comprises the larger sections ; many of these, as in 
England, being further subdivided into zones characterized by peculiar 
or specially abundant species of fossils: ? 
Purbeckien,? fresh and brackish water beds with Corbula forbesiana, Physa 
wealdiana, Valvata helicoides, and other Purbeck species. Found in the 
Jura, lying conformably on top of Portlandien, near Morteau, valley of the 
Doubs. 
Portlandien, a well-developed group of limestones, divisible in the Cote d’Or 
into an upper zone with Trigonia boloniensis and Pinna supra-~jurensis, and 
a lower zone with Ammonites gigas. 'The group extends into the Swiss 
Jura, northwards down the valley of the Meuse, and reappears on the coast 
near Boulogne-sur-Mer, where it attains a thickness of above 200 feet, and 
is divisible into three bands: a lower stage (Trigonia Micheloti, T. bar- 
rensis, T. boloniensis, Cardium dissimile, Astropecten Loriolii, Hemicidaris 
purbeckensis, &¢.); a middle stage (Cardiuwm morinicum, Ostrea ex- 
pansa, Ammonites biplex, Acrosalenia Kénigii} ; and an upper stage (Am- 
monites gigas, &c.). 
Kimmeridien = Kimmeridge clay, divisible into three zones as under: 
e. Virgulien (Hxogyra (Ostrea) virgula). 
b. Ptérocérien (Pteroceras Ocean). 
a. Astartien (Calcaires a Astartes), Sequanien in part, Ostrea deltoidea 
(Fig. 373), Astarte minima. 
Corallien. Some authors take the upper part of this group into a separate 
section under the name of Sequanien, largely developed in the east of 
France, where it consists of massive limestones sometimes 400 feet thick. 
In the Ardennes also this group sometimes exceeds 400 feet in thickness, 
and consists of limestones. The Corallien in France and Switzerland 
presents three zones: Ist, an upper set of fine white earthy or siliceous 
limestones with Nerinza, Diceras arietinum, &c., apparently absent in Eng- 
land ; 2nd, a middle group of coral limestones (Thecosmilia, Montlivaltia, 
Isastrza, Thamnastrea, &c.); 3rd, a lower echinoderm zone (Cidaris flori- 
gemma, Glypticus hieroglyphicus). 
Oxfordien (including Argovien and Callovien) consists of marls, sometimes 
calcareous or ferruginous. The following zones in descending order have 
been observed in the Céte d’Or: 1. Ammonites plicatilis, Pholadomya 
parcicostata; 2. Ammonites babeanus, Pholodomya ampla ; 3. Ammonites 
biplex, A. canaliculatus, A. Henrici, A. eucharis, Trigonia clavellata ; aud 
large sponges (Scyphia obliqua and other species) ; 4. Ammonites cordatus, 
A. perarmatus, A. oculatus ; 5. Marnes Calloviennes with Ammonites callo- 
viensis, A. macrocephalus, A. athleta (= Kellaways Rock). In the Bou- 
lonnais the subdivisions in descending order are: 1. Clay with Ammonites 
Mantelli; 2. Clay with A. cordatus; 3. Clay and marly limestone with 
A, Lamberti; 4. Clay with A. macrocephalus. 
Bathonien or Grande Oolithe, composed in the North of France of the 
following lithological zones in descending order: Calcaire a Polypiers, 
Calcaire de Ranville, Oolithe de Caen, Calcaire de Caen, Grande Oolithe, 
Terre & Foulon. In this region the paleontological zones are in descending 
order: 1. Terebratula lagenalis; 2. Rhynchonella elegantula ; 3. Rhyncho- 
nella decorata or Rh. Hopkinsii; 4. Cardium pes-bovis ; 5. Clypeus Plotiz ; 
6. Ostrea acuminata. In the east of the country (Cote d’Or) the following 
zones have been made out in descending order—l. Flags and marls, with 
1 See a full bibliography of works on the Jurassic Rocks of N.W. France, in an 
excellent paper on these rocks by Mr. J. F. Blake, Q. J. Geol. Soc. 1881, p. 497. 
Consult also D’Orbigny’s Paléontographie Frangaise—Terrains Oolitiques,”’ 1842-1850; 
- D’Archiac, Paléontologie de la France, 1868. 
2 Mr. J. F. Blake, in the paper already cited, proposes to class the Purbeck and 
Portland limestone with their equivalents under the term Portlandian as the uppermost 
group of the Jurassic system. Below these beds he places the middle and lower Port- 
land as the “ Bolonian group,” resting upon the Virgulian beds of the Kimmeridgian, 
and including strata lower in position than the true Portland beds, and which are not 
found in the south of England. 
