OSTRBA. 



0{- 



umcronata of Norwich, is in the British Museum. 0. hippopodlnm, Nilsson, from 

 the Upper Chalk of Kopingc, is in the Lund ]\Iuscuin. The specimens of 0. hippo- 

 jjudiuiu figured by Goldfuss from the Cenomanian of Ussen, are in the Munich 

 Museum. The examples of 0. vesicular i.i figured by William Smith came from 

 Norwich and are in the British Museum. Tlie original of (hijplixa (jlohosa var. 

 depressa, Sowerby (in Dixon), cannot be found ; the specimens of O.S'frea figured by 

 the same author (Dixon, pi. xxviii, figs. 22, 23), from the zone of Holastersuhgloho.^iis 

 near Warminster, are in the British ]\luseum. The specimen figured by S. P. 

 Woodward as 0. vesiculosa from the Upper Chalk of Sussex, is also in that Museum. 

 Acicula filata, Etheridge, from the Totternhoe Stone of Burwell, is in the Sedgwick 

 Museum. 



Fio. 182. — Osd-ea fc»'icK?aris, Lam. Zone of Osfrea ZunaJa, Triminghani. Dr. Rowe's Collection. Left 



valve. X J. 



Distiihntion. — Lower Greensand (Ferruginous Sands) of Shanklin. Gault of 

 Folkestone. Cambridge Greensand. Upper Greensand (zone of Schlmnbachia 

 rostrata) of the Isle of Wight. Upper Greensand (zone of Pecten aspcr) of War- 

 min.ster. 



Chalk Marl (zone of SrhhenJiarida rarians) of Folkestone, Offham, and Burwell. 

 Cenomanian (Meyer's bed 11) of Beer Head. Cenomanian Sandstone of 

 Wilmington. 



Zone of Holaster suhijlohosus of Chilcomb (IIant.s), Glynde (Lewes), Burham, 

 Arlesey, Ickleford (near Hitchin), Cheri-y Hinton, Burwell, and Isleham. 



Zone of Rhi/iichonelli Gavieri of the South Devon coast and Dover. Melbourn 

 Rock, ^lelbourn. 



49 



