EOCENE FOSSILS. 
411 
MELANIin.E. 
Coidustjjlus gloho.sus Edwards ]MS. 
PALUUESTRINID.E. 
Faludcstrinri ambigua Edwds. MS., 
si(hpulchra Edwards MS., 
Tomickia microstoma (Desliayes), 
teres Edwards MS., 
tuba (Desliaj'es), 
Pyrgula indchra (Kaincourt), 
Bithynella toebstcri (Moms), 
Stenothyra parkinsoni (Morris). 
VIVIPARID.E. 
Vivipara aspersa (Michaud), 
lenta (Solander). 
NERITID^. 
Neritina consobrina Fer. , 
globulus (Fer.), 
passyana Desh., 
vicina Melleville, 
— V. jaspidea De.sli. 
U.VIONID.E. 
Unio edwardsi S.V.M’ood, 
michntidi Desh. 
ENIOXID.E. 
Unio subparedlcla S. V.M'ood. 
CORBICULin.E. 
Corbicida adunca (Edwards MS.), 
ultirupestris (Edwards MS.), 
cmccjis (S.V. Wood), 
britannica (Desh.), 
charpentieri (Potiez & Michaud), 
cordata (Morris), 
erassa (Desliayes), 
cuneiformis (3 . Sow.), 
deperdita (Lamarck), 
/ (fie A /e « s ( R ick 111 an ) , 
forbesi (Desliayes), 
intermedia (Melleville), 
obovata (.J. Sow. ), 
pullastra (S. V.AVood), 
sororculn (Edwards MS.), 
strigosa (S.V.M'ood), 
subdepressu (Edwards ^IS.), 
tellinella (Fer.), 
trigona (Desh.), 
tumida (S.V. Wood). 
The Oligocene (oA.tyos, few ; Katvos, recent) the fluvio-marine serie.s 
of Forbes, is considered to be the representative of the early stages of 
the Miocene period in the Britisli Isles; it shows a still closer approxi- 
mation to the pre.sent fauna than that of the preceding strata, its 
remains possessing so great an interest and beauty that a .short sum- 
mary of the situation and character of the different beds is given. 
Its deposits consist of marls, sands, clays, and limestones, and are 
confined to the Isle of Wight and to Hampshire, the estuarine and 
freshwater conditions under which the strata were mainly deposited 
being shown by the abundance of Cerithium, Potamomya, Corbicida, 
Limncea, etc. 
The Oligocene deposits are subdivided into four chief beds, desig- 
nated by the names of the localities where they are well displayed : 
the Headon, the Osborne, the Bembridge, and the Hempstead beds. 
The Headon series are exhibited at Totlands and Colwell Bays and 
Headon Hill, Planorhis euomphalus Sow’, being the characteristic 
fossil of the series. The beds may be subdivided into an upper, a 
middle, and a lower series. The middle Headon is mainly marine or 
brackish. The lower series is composed of clays and marls with 
intercalated beds of freshwater limestone, and is also displayed at 
Hordwell Cliffs in Hampshire. The upper Headon is freshwater, and 
shows characteristic Limmean limestones, shales, and marls. 
The Osborne series is visible at St. Helens, Osborne, Headon Hill, 
Colwell, Totlands, and Gurnet Bays. 
