ZONE OF AMMONITES JURENSIS. 



89 



Astarte lurida, Sow. 

 Posidonomya Bronni, Volts. 

 Nucula Hiiusmanni, Hoem. 



— ovum, Sow. 

 Gresslya gregaria, Roem. 

 Lima bellula, ? Lyc. and Mor. 

 — gigantea, ? Sow. 



Leptsena Moorei, Dav. 



— liasina, Bouch. 



— granulosa, Dav. 

 Thecidium rusticum, Moore. 



— Boucbardii, Dav. 

 Lingula Beanii, Phil. 



Acrosalenia crinifera, Quenst. 

 Pseudodiadema Moorei, Wi-iyht. 



CONCHIFERA. 



Tancredia Iseviuscula, Lyc. 

 Placunopsis sparsicostatus, Lyc. 

 Inoceraraus dubius. Sow. 

 Monotis substriata. Gold/. 

 Area insequivalvis, Goldf. 

 Cucullsea Miiuster, Ziet. 



Brachiopoda. 



Spirifer Ilminsterensis. Dav. 



— Miiiisteri. Dav. 

 Rhynchonella pygmaea, Mor. 

 Terebratula globuliu:i, Dav. 

 — Lycelti, Dav. 



ECHINODERMATA. 



Pentacrinus. 



The Zone of Ammonites Jurensis. 



Synonyms. — "Lias Zeta," Quenstedt, ' Der Jura Uebevsiclitstafel,' p. 293. "Zone des 

 Amm. torulosus iind zone des Amm. Jurensis," Oppel, ' Juraformation,' p. 296. " Marnes 

 d'Aresclie, et Marnes de Pinperdu/' Marcou, franc- comtois, les Uoches, 'Du Jura,' p. 119, 

 " 9*" etage Toarcien (pars, sup.)," d'Orbigny, ' Cours. element, de Paleontologie,' p, 469 

 (sect, at Tliouars h to /). " Sands of the Inferior Oolite," Smith, De la Beche, Cony- 

 beare, and other English authors. " Cephalopoda bed and Upper Lias Sands," Wright, 

 'Quart. Jour. Geol. Soc.,' vol. xii, p. 292, 1856. "Ammonite Sands," Hull, 'Mem. of 

 the Geol. Surv. Country around Cheltenham,' p. 25, 1857. " Cynocephala stage," Lycett, 

 'Cotteswold Hills,' p. 16, 1857. "Jurensis bed," Wright, 'Quart. Jour. Geol. Soc.,' 

 vol. xiv, p. 25, 1857. 



This youngest member of the great Lias formation has a limited geographical range ; 

 for like other unconsolidated arenaceous deposits, it has been extensively affected by 

 denudation. It is well developed in the counties of Gloucester, Somerset and Dorset, 

 and at Blue Wick, on the Yorkshire coast. It may be advantageously studied at the 

 latter locality, and in the fine section at Erocester Hill, and in other smaller exposures in 

 the Nailsworth and Brimscombe Valleys in Gloucestershire. The following section of 



12 



