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the points of iutersection of these witli the lines of growth; in A.steUaris 

 the shell is more compressed, the keel smaller and not so obtuse ; the 

 digitations of the lobes are likewise more complicated, and the saddles 

 longer and narrower. 



Locality and Stratigraphical Position. — This Ammonite characterises 

 a well marked zone of life in the Lower Lias, which was well shown at 

 Bredon during the cutting of the Bristol and Birmingham Railway, and 

 from whence I obtained all my best specimens. The rock consisted of 

 dark -gray bluish shales and marls, with irregular and inconstant bands 

 of limestone. This Ammonite is found near Statford-on-Avon, in 

 Warwickshire ; it is collected in great abundance between Lyme Regis 

 and Charmouth, where the shells are replaced and their septse filled with 

 crystallised carbonate of lime. These beautiful fossils are called "Tortoise 

 Ammonites" by the local collectors. The young examples of this species 

 found with A. planicosta, Sow., in the Marston mai'ble of Somersetshire, 

 which belongs to the zone of A. obtusus, have been figured by Sowerby 

 under the name of A. Smithii. 



In Robin Hood's Bay, on the Yorkshire coast, I have found this 

 species, which, however, is very rare in that county, A. stellaris being here 

 the dominant form, and called A. obtusus in most of the public and private 

 collections. 



On the continent of Europe it has been found in France, in the 

 environs of Saint Ramber, (Ain,) and in the province of Luxemburg, at 

 Ethe. It is found in South Germany in many localities. Professor 

 QuENSTEDT mistook this species for A. Turneri, Sow., and figured it as 

 such ; the Professor, however, recognised the stratigraphical importance 

 of this form, as he found it characteristic of a zone, which he called 

 " Turnerithone." It is found at Balingen, Oster-dingen, Betzingen, and 

 Betzgenreith. 



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