ZONE OF AMALTHEIIS 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 up[)er 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 Cephalopoda-hQ^, sixteen feet thick ; 

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



5. The Inferior OoHte Limestone, similar to the Frocester 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 Cotteswolds in this region. 



At South Petherton 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 Amaltheus maryaritatus and Amal. Engelhanlti, 

 and several Lamellibranchiata and Brachiopoda, with their tests iu 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, (TOrb. 

 Harpoceras Normanianum, cCOrb. 

 Phylloceras heterophyllus amalthei, 

 Quenst. =;zetes, cTOrb. 



Pleurotomaria similis, Sow. 



— undosa, Heslong. 



— Sabrina, Tate. 

 Crypt2enia expansa, Sow. 



Gasteropoda. 



Chemnitzia Blainvillei, Munst. 

 Discohelix aratus, Tate. 

 Eucyclus imbricatus. Sow. 



