XXXI MOLLUSCA OF SOMERSET. 
Vitrea cellaria, Miiller. 
Vitrea nitidula, Draparnaud. 
*“Punctum pygmeum, Draparnaud. 
Pyramidula rupestris, Draparnaud. 
Pyramidula rotundata, Miiller. 
*“Helicella virgata, da Costa. 
“Helicella caperata, Montagu. 
Helicella barbara, Linné. 
Hygromia hispida, Linné. 
“Hygromia rufescens, Pennunt 
*“Vallonia pulchella, Miller. 
Vallonia excentrica, Sterii. 
Helicigona lapicida, Linné. 
“Helix aspersa, Miller. 
*Helix nemoralis, Linné. 
Ena obscura, Miiller. 
*Jaminia cylindracea, da Costa. 
*Jaminia muscorum, Linné. 
Clausilia bidentata, Strim. 
The comparison of the molluscan fauna of Brean Down 
with that of the islets known as the Steep Holm and the Flat 
Holm is of interest, because the islets are of the same geologi- 
cal formation (Carboniferous Limestone), and were at one 
time connected with the peninsula of Brean Down, which may 
also be termed an island of limestone. The species marked 
with an asterisk in the above list have been noted by Mr. 
Francis Knight as occurring on the Holms, with * Hyalinia 
several species,” (presumably the three species of Vitrea given 
above), also Pupa secale, Draparnaud; Clausilia laminata, 
Montagu; and Pomatias elegans, Muller; a trio I failed to 
note on Brean Down, but which doubtless occur there. The 
holocene deposit on Brean Down has been already alluded to 
(p. Xvi). 
i. THE UPLAND AREA: 
The region of deep marls and clays, limestones and sand- 
