ZONE OF AMMONITES MARGARITATUS. 



83 



upper, a rock-bed of an impure limestone, weathering blue or brown in the interior. In 

 the eastern part of the district it is highly ferruginous, and varies from one to ten feet in 

 thickness. The rock-bed forms the surface of the tabulated promontories which produce 

 such picturesque features along the flanks of the Cotteswold Hills, and around many of the 

 outliers, while the steep, fertile banks which descend from the edges of the platforms to 

 the Lower Lias plain are composed of the underlying beds of sand. 



At Leckhampton Hill the thickness of this formation is 115 feet, and this is its 

 estimated general thickness around the Cotteswold Hills. The zone of Ammonites spinatus 

 is so closely incorporated with the Marlstone rock-bed that it must be included in this 

 stage, of which it forms the uppermost portion. 



Fomls from the Marlstone. 



Vertebrata. 



Vertebrae of IcLthvosaurus. | Teeth and scales of fishes. 



Cephai-opoda. 



Belemnites eonipressus, Stahl. 



— paxillosus, Schloth. 

 Nautihis striatns, Soiv. 



— intermedius, Sow. 



Ammonites margaritatus, Montf. 



— Englehardti, d'Orhig. 



— Normaniamis, (TOrbig. 



— heterophyllus amalthei, Querist. 



Gasteropoda. 



Pleurotomaria Anglica, Sow. 



— vindosiis, Schiibl. 



— expansa, Sow. 



Chemnitzia undulata, Ziet. 

 Turbo orion, d'Orhig. 

 Trochus imbricatus, Sow. 



Pholadomya ambigua, Sow. 

 Pleuromya unioides, Itvm. 



— rotuiidata, Gohlf. 



— Aldnini, Brong. 



— donaeiforme, Goldf. 

 Ceromya lineata, Will. 

 Arcomya elongata, Hum. 

 Unicardium cardioides, Fhil. 

 Cardium truncatum, Phil. 

 Cardinia crassiuscula, Sov). 



— crassissima, Sow. 

 Gouiomya capricorni, Wr. 



CONCHIFERA. 



Cypricardia cucullata, Goldf. 

 Modiola scalprum. Sow. 

 Limea acuticosta, Goldf. 

 Monotis ineequivalvis, Sow. 

 Lima Hermanni, Volfz. 



— duplicata, Sow. 



— pectinoides, Sow. 

 Pecten diversus. Buck. 



— EEqiiivalvis, Sow. 



— cinctus, Soio. 

 Gryphsea gigantea, Soiv. 

 Ostrea. 



