238 



localities in Gloucestershire; Weston, near Bath; Saltford, near Bristol; 

 Lyme Regis; and Robin Hood's Bay, Yorkshire. Mr. Jones found it at 

 Pui-ton on Severn.* Foreign Localities: — It characterises the Lower Lias 

 in the zone of Gryphcea arcuata in many Departments in France, as 

 Cher, Jura, Ain, Meurthe, and Cote-d'Or ; in Swabia it is collected at 

 Vaihingen, Mohringen, Bebenhausen, and Nurtingen ; for the other 

 countries in Europe in which it is found the reader is referred to the 

 table of synonyms. 



History. — Fii-st figured by Sowerby; afterwards by Zieten, d'ORBiGNY, 

 and Haueb. These figures are all good, and leave but little to be desired. 



Ammonites rotiformis, Sowerby, (Plate 3, fig. 1.) 



Ammonites rotiformis, Soiverly, Mineral Conch., vol. 5, tab. 453, 1824. 

 OBLiQUE-cosTATUS, Zieten, die Versteinerungen "Wiirtembergs, 



tab. 15, fig. 1, 1830. 

 rotiformis, Zieten, die Versteineningen Wiirtembergs, tab. 26, 



fig. 1, 1831. 

 ROTIFORMIS, cP Orligny, Paldontologie Fran§aise tei\ Jurassique, 



plate 89, 1844. 

 OBLIQUE-COSTATUS, Hauer, Jahrbuch geologischen Reichsanstalt, 



Band 4, p. 736, 1853. 

 ROTIFORMIS, Studer, Geologic der Schweiz, Band 2, p. 30, 1853. 

 ROTIFORMIS, Hauer, die Cephalopoden aus dem Lias der Alpen, 



tab. 1 and 9, s. 13, 1856. 

 ROTIFORMIS, Quenstedt, der Jura, p. 67, tab. 7, fig. 1, 1858. 

 ROTIFORMIS, Opjjel, die Juraformation, p. 77, 1856. 

 Diagnosis. — Shell discoidal, compressed; back ti-icarinated ; whorls 

 numerous, quadrate, slightly involute, and strongly costated ; costae from 

 27 to 30 in a whorl, simple, strong, arched, and terminating near the 

 back in a large, round, obtuse txibercle ; back lai'ge, flat, with a median 

 keel, two lateral sulci, and marginal carin?e ; apertiu-e quadrate, depressed, 

 sinuous anteriorly. 



Dimensions. — Transverse diametei", 7 inches; height of aperture, 1| 

 inches; width of aperture. If inches. M. d'ORBiGNY's specimen: — 

 width of the last whorl, -f-^; portion overlapped of last whorl, -^^-y 

 thickness of last whorl, -^-^-^ ; width of the umbilicus, jy^. 



Description. — Shell discoidal, compressed, with quadrate whorls, 

 strongly ribbed, and slightly involute. In the specimen I have figured, 



♦ Proceedings of the Cotteswold Club for 1863, p. 135. 



