JURASSIC PERIOD. 



449 



Sinemurian (Lower Lias, named from the locality at Semur) ; 2, Liasian 

 (Middle Lias); 3, Toarcian (from the locality at Thours) ; (II.) in the Oolite, 

 — 1, Bajocian (the inferior part of the Lower Oolite, named from the locality 

 at Bayeux); 2, Bathonian (the Great Oolite, Bath Oolite); 3, Callovian (Kel' 

 loway Roek) ; 4, Oxfordian (Oxford Clay); 5, Corallian (Coral Bag); 6, Kim- 

 meridyian (Kimmeridge Clay); 7, Portlandian (Portland Oolite). 



In the French Juras the most of the above subdivisions may be traced. 

 There are, — 



1. The Lower Lias, — a Lias limestone, called also Gryphite limestone, from the 

 abundance of the fossil Gryphsea arcuata ; 2, the Middle Lias, marls ; 3, the 

 Upper Lias, bituminous schists, in some places called Posidonia schists, from 

 the abundance of Posidonia Bronnii, with a rough limestone above. The Lias 

 is overlaid by (1) the Lower Oolite; (2) the Oxford Oolite; (3) the Coral and 

 Astarte limestone, and Portland beds. 



The famous beds of. Lithographic slate at Solenhofen, affording remains of 

 many Insects, several species of Saurians, seven of Pterodactyls, etc., are situated 

 in the district of Pappenheim in Bavaria, and are of the age of the Middle 

 Oolite, or that of the Coral Limestone. 



II. Life. 



1. Plants. 

 The land-plants of the Jurassic period are mainly Ferns, Conifers, 

 and Cycads, as in the Triassic. Leaves and stems are found in many- 

 Figs. 671-673. 



Fig. 671, section from near Lullworth Cove, showing stumps of trees (a) in the Portland 

 "dirt-bed;" 672, Leaf of a living Zamia (X <& )', 673, stump of the Cycad Mantellia (Cy- 

 cadeoidea) megalophylla (X ab). 



of the strata, and remains of a forest in what is called the Portland 

 dirt-bed (fig. 671) (lower part of the Purbeck), the trees of which 



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