130 The Offictal Guide to the 
and Odostomia, the latter, as aranged by Mr. 
Jeffreys, a very extensive genus of a 
minute shells. 
Of Lanthina rotundata, the beautiful violet-colonred 
raft-building shell, an oceanic species occasionally cast 
ashore on the southern portions of England and 
Treland, we have already spoken at p. 113, and glanc- 
ing at the pretty spiral shells of Audima, Natica, and 
Trichotropis, we notice the dilated lip and wing-like 
processes of the handsome genus Aforrhazs, known as 
*¢Spout Shells,” and arrive at the family Bucctnipa, © 
the first genus of which is Purpura, P. lapillus, being 
our well-known Dog Whelk, the deadly enemy of the 
mussel and other bivalves, from which after perforating 
the valve with its spiny, tongue, it extracts the soft 
parts ; it also yields a coloured fluid on pressing the ~ 
operculum, at first white, but afterwards becoming 
blue, which was formerly used by the Irish as a 
dye. 
There are several other genera of strongly-marked 
shells which we cannot stop to particularise, as 7rzZon, 
Murex, Fusus, Vassa, etc., till we come to the pretty 
httle Mare sinella levis, the still prettier Cyprea europea, 
the only “British cowry, followed by Ovwla patula, a 
near relative. 
The family Buttip& contains several genera of sin- 
gular shells. Cylichna cylindracea is a cylinder of nearly 
the same breadth throughout, a prettily-marked Acéeoz, 
Bulla hydatus, one of the Bubble shells, Scaphander 
lignarius, and Philene apferta, a species in which the 
shell is wholly internal and concealed under the 
mantle, brings us to the end of the family and at the 
same time to that of the case. 
Passing through the Mammalian Room we come 
to the corridor devoted to Osteology, on the left-hand 
side of which are four small table cases ; in. é 
