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The Upper Lias. — The sands of the Upper Lias forming the ujjper 

 portion of this zone are characterized for the most part by Ammonites 

 belonging to the group Falcifcri, as Ammonites opalinus, Rein., and A. 

 radians, Schloth. ; Ammonites Jurensis, Ziet., and A. insignis, Schubl., 

 both belonging to other groups, are likewise associated with them. 



The clays of the Upper Lias, forming the lower part of the zone, are 

 eveiy where distinguished by other species of Falciferi, as Ammonites 

 hifrons, Brug. ; A. serpentinus, Schloth. ; and numbers of the group 

 Planulati, as Ammonites communis, Sow. ; A. anguinus, Rein. ; and A. 

 Jibulatus, Sow. 



The Middle Lias. — This is divisible into five zones, each characterized 

 in descending order by : — 1. Am,monites spinatibs, Brug.; 2. A. marga- 

 ritatus, Mont. ; 3. A. Capricornus, Schloth. ; 4. A. Ibex, Quenst. ; 5. A. 

 Jamesoni, Sow. 



The Lower Lias is divisible into seven zones. These are : — 1. Zone 

 of A. raricostatus, Ziet. ; 2. A. oxi/iiotus. Quenst. ; 3. A. obtusus, Sow. ; 

 4. A. Turneri, Sow. ; 5. A. Bucklandi, Sow. ; 6. A. angulatus, Schloth. ; 

 7. A . platiarbis. Sow. 



Complicated as these sub-divisions may at first sight appear to those 

 who have regarded the Lias merely as a great clay deposit, with a uniform 

 fauna throughout, still their accvu-acy may be clearly demonstrated in the 

 grand section on the Dorsetshire coast, extending from near Bridport 

 Harbour on the east, to Pinhay Bay on the west. 



Within these limits the entii-e series of beds rise beneath each other 

 on the shore, and are exposed in the cliffs, so that this coast section may 

 be said to be complete from the great arenaceous deposit of Upper Lias 

 sand, containing Ammonites opalinus, with each succeeding zone of the 

 Upper, Middle, and Lower Lias, down to Ammmdtes planorbis, and its 

 Ostrea series resting on the Avicvla contorta beds of the Trias formation. 



In the table on the following page I have placed the different zones of 

 the English Lias in correlation with those of Germany, so well described 

 by Professors Quenstedt, Oppel, Fraas, and others ; those of France, 

 by the late M. A. d'ORBiGNY; those of England, by Sir Roderick 

 Murchison, Sir Henry De La Bbche, and the Rev. W. D. Conybeabe. 



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