III. 
REMARKS ON THE LAND MOLLUSC A, WITH REFERENCE TO 
THEIR INVESTIGATION IN HERTFORDSHIRE. 
By John Hopkinson, E.L.S., E.G.S., E.B.M.S. 
Read at St. Albans, 10 th January , 1884. 
The Land and Eresh-water Mollusca of the British Isles are few 
in number, comprising only 32 genera and about 130 species ; they 
are widely distributed, for at least half the species may be found 
almost anywhere within the radius of a few miles; to obtain them 
is an easy matter, requiring very little apparatus; and as most of 
them are sufficiently well-represented by their shells, a collection 
illustrative of these, the testaceous kinds, is easily formed. They 
are therefore a group peculiarly well suited for study by those who 
have but little leisure ; and I venture to plead for their investigation 
by members of the Society residing in distant parts of our county, 
and for aid in a complete search for them in the neighbourhood of 
"Watford. In order to endeavour to awaken an interest in our 
terrestrial Mollusca. I offer the following remarks, leaving 
the fresh-water forms for the present in the hope that some other 
member may contribute an introduction to their study. 
The British Land Mollusca form the order Pulmonieera (air- 
breathers)* 4 of the class Gastropora (belly-footed), and they consist 
of 83 species which are comprised in 19 genera, these again being 
grouped into 6 families, as in the following table :— 
Arionidje ... 
Limacidte ... 
Testacellidh] 
Helicid.® ... 
Carychiidh: 
CyCLOSTOMATIDHJ 
Avion, Eerussac. 
Geomalacus, Allman. 
Amalia, Moquin-Tandon. 
Umax, Linnaeus. 
Testacella, Cuvier. 
’Succinea , Draparnaud. 
Vitrina, Draparnaud. 
Zonites, De Montfort. 
Helix, Linnaeus. 
Bulimus, Scopoli. 
Pupa, Lamarck. 
Vertigo, Muller. 
Balia, Prideaux. 
Clausilia, Draparnaud. 
Cochlicopa, Eerussac. 
Achatina, Lamarck. 
Carychium, Muller. 
Cyclostoma, De Montfort. 
Acme, Hartmann. 
* Or, with the Limnseidse which breathe both air and water, the Pulmono- 
branchiata of Dr. Gwyn Jeffreys and other authorities. 
vol. in .—part i. 
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