70 



LOWER LIAS. 



Fiona diluviana {Zieten, pi. 55, fig. G). 

 Pholadomya glabra, Agass. 

 Terebratula psilonoti, Quenst. 

 Rhynclionella variabilis, Schloth, 

 Spirifera Walcotti, Sow. 



Pseudo-diadema (spines). 

 Cidaris Edwardsii, Wr. 

 Pentacrinus tuberculatus. Mill. 

 Isastrssa Murchisoni, Wr. 



3. The Zone of Ammonites Turneei. 



Si/nonijms. — "Hauptpentacrinitenbank des untern Lias," Quenstedt, 'Mozgeb.,' p. 152, 

 1843. " Lumaclielle de Pentacrinites basaltiformis," Marcou, ' Jura salinois,' p. 47, 1846. 

 "Die Scbicliten des Pentacrinus tuberculatus' Oppel, ' Juraformation,' p. 44, 1856. 

 " Tuberculatus-bed," Wright, ' Quart. Journ. Geol Soc.,' vol xv, p. 25, 1858. "Marne 

 de Strassen,'' Dewalque et Cbapuis, Tossiles de Luxembourg,' 1853. "Marne de 

 Strassen," Dewalque, 'Descrip. du Lias de Luxembourg,' 1857. Zone oi Ammonites 

 Turneri, Wright, ' Quart. Journ. Geol. Soc.,' vol xvi. p. 403. 



This subdivision of the Lower Lias forms a well-marked zone of life. The beds 

 consist of light-coloured argillaceous limestone, of hard grayish limestone, or of deep-blue, 

 shelly, indurated shale, interstratified with beds of dark-coloured clay. Many of the slabs 

 of limestone are covered with shells and portions of the stem and side arms of Pentacrinus 

 tuberculatus, Mill. From one of these slabs, collected at Frethern or Purton, in Gloucester- 

 shire, Miller's original specimen of this Crinoid was obtained. 



GloucestersJiire and Wanoickslnre. — The zone of Ammonites Turneri was exposed at 

 Bredon, in the deep cuttings of the Bristol and Birmingham Railway, from whence many 

 of my specimens were obtained. In the A^ale of Gloucester portions of these beds are 

 sometimes laid open in making drains, as at Badgeworth and Hardwick ; and many fine 

 slabs are occasionally procured from the river-section at Purton. I know of no locality 

 in Gloucestershire, where the entire series is exposed. My friend. Dr. Oppel, referred the 

 Saurian beds of Brockeridge Common to this series, supposing them to be the equivalent 

 of the Saurian beds at Lyme, which, however, appertain to the zone of Ammonites Turneri; 

 the description I have already given of the Am. planorbis beds and their correlations prove 

 that the beds at Brockeridge Common represent the Am. planorbis series. In Warwick- 

 shire the Am. Turneri beds constitute the base of what is called in that county the 

 " Cardinia-series," in which are included all the strata of the Lower Lias between the 

 Am. Turneri and Am. raricostatus beds, and which are characterised by different forms of 

 the genus Cardinia. 



DorsetsJiire. — At Lyme Regis the Ammonites BucJclandi or Lima series is overlain by 

 thick beds of clay and slaty marls containing many Enaliosaurian skeletons, with numerous 

 fishes, in fine preservation ; these strata are known to local collectors as the Fish- and 



