ZONE OF AMALTHEUS MARGARITATUS. 



95 



1. The Lower Lias shale and limestone of the Valley of the Severn; thickness unknown. 



2. The sands, shales, and clays of the Middle Lias ; 186 feet in thickness. 



2'. The hard, brown, fossiliferous Rock-bed, or Marlstone capping the terrace ; 

 12 feet. 



3. The Upper Lias shales in thin beds, with nodules of limestone at the top ; 10 feet 

 thick. 



4. The Upper Lias sands, containing hard sandy nodules and lenticular concretions 



in the upper part, and brown, ferruginous, loose sand in the lower portion ; 123 feet 

 thick. 



4'. Hard, brown, calcareous, sandy bands, freely speckled with granules of ferri- 

 silicate, and interstratified with layers of softer sand containing Ammonites, Belemnites, 

 Nautili, &c., in considerable numbers, and forming a Cephalo2)oda-\iQ(\, sixteen feet thick ; 

 this is correlative with the one to be described at Erocester Hill. 



5. The Inferior Oolite Limestone, similar to the Erocester and Painswick rocks, 

 forming the freestone or building-stone of the district. Eighty feet thick. 



6. The Fullers Earth ; 128 feet thick. 



7. The Great Oolite, forming the summit of Symond's Hall Hill and the plateaux 

 of the Cottes wolds in this region. 



At South Pctherton in Somersetshire the Marlstone was formerly extensively worked 

 for road-material; the beds are thin but very fossiliferous, and many fine specimens 

 were obtained therefrom. All my finest AmaUheus margaritatus and Amal. Engelhardti, 

 and several Lamellibranchiata and Brachiopoda, with their tests in a beautiful state 

 of preservation, came from this locality. 



Fossils from the Marlstone or Margaritatus-zone in Gloucestershire. 



Vertebrae of Ichthyosaurus. 



Vertebrata. 



I Teeth and scales of Fishes. 



Belemnites clavatus, Blainv, 



— Milleri, Phill. 

 Nautilus striatus, Sow. 



— truncatus, Sow. 

 Amaltheus margaritatus, Montf. 



Cephalopoda. 



Amaltheus Englehardti, d'Orb. 

 Harpoceras Normanianum, d'Orb. 

 Phylloceras heterophyllus amalthei, 

 Quenst. = zetes, d' Orb. 



Pleurotomaria similis, Sow. 



— undosa, Deslong. 



— Sabrina, Tate, 

 Cryptsenia expansa. Sow. 



Gasteropoda. 



Chemnitzia Blainvillei, Miinst. 

 Discohelix aratus, Tate. 

 Eucyclus imbricatus, Sow. 



