70 



LOWER LIAS. 



Pinna diluviana {Zieten, pi. 5.5, fig. G). 

 Pholadomya glabra, Agass. 

 Terebratula psilonoti, Quenst. 

 Rhyncbonella variabilis, Schluth. 

 Spirifera Walcotti, Sow. 



Pseudo-diadema (spines). 

 Cidaris Edwardsii, Wr. 

 Pentacrinus tuberculatus. Mill. 

 Isastraea Murchisoni, Wr. 



3. The Zone of Ammonites Turneri. 



Sj/no?iyms. — "Hauptpentacrinitenbank des untern Lias," Quenstedt, Tlozgeb.,' p.l52, 

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

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

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

 de Strassen," Dewalque et Chapuis, 'Fossiles 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. ]\Iany of the slabs 

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

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

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



Gloucestershire and Warioichshire. — 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 Vale 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 Burton. 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 difi'erent forms of 

 the genus Cardinia. 



DorsclsJdre. — At Lyme Regis the Ammonites BucMandi 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 



