124 The Official Guide to the 
shells, the inhabitants of which are gregarious, living 
on walls, under stones, and at the roots of plants. 
The genus Vertigo, Whorl Snails, consists, according 
to Gwyn Jeffreys, of nine species of minute molluscs, 
much resembling in form and habits the preceding 
genus ; and the same may be said of the tiny Bala 
perversa ; also of the species of Clauszlia, Cochlicopa, 
Achatina, Carychium, Cyclostoma (found on nettles 
growing on the chalk at Whitlingham), and Achme, 
which complete the contents of the case. 
Case IIIl.—Marine Shells. 
Class BRACHIOPODA. When describing the 
shells in the Foreign Collection, we have already had 
occasion (p. 115) to speak of the members of this 
remarkable Order. According to Mr. Gwyn Jeffreys, 
it comprises two families, containing three genera and 
SIX Species. 
We now arrive at the true marine Bivalves, Mr, 
Gwyn Jeffreys’ Class .CONCHIFERA, 9)@imes 
LAMELLIBRANCHIATA, the first family of which 
contains one genus and two British species, Anzomza 
ephippium and A. patelliformis, both of these are in 
the collection, dredged in Loch Fyne. From their 
appearance, these shells are known as ‘“‘silver shells” ; 
the animal inhabits the littoral zone from low water 
to eighty or ninety fathoms, and is generally dispersed 
on our shores, anchoring itself to rocks and shells by 
a plug, passing through an orifice in the lower valve. 
The next family, that of Osrrrimpa&, is monopolised 
by the most delicious of Molluscs, our common (?) 
Oyster, Ostrea edults. This species is too well 
known to need description, and good specimens 
are in the collection, some of them showing the 
beautiful pearly deposit which covers the inside of the 
