16 A NEW MONOGRAPH OF BRITISH MOLLUSCA. 
real shape and colours in black and white. The drawing revives 
pleasant memories of dredgings in muddy ponds fringed with rushes 
and overhung with willows. 
Or if you are a malacologist as well as a conchologist—using 
the terms in a narrowed sense—this drawing of Unio pictorum, 
from Clumber Lake, Notts, graphically rendering the relationship 
between the animal and its shell, will take your thoughts back 
to days of experiments with magenta dyes on ciliary action and 
Brownian movements. 
Some of these illustrations are examples 
of painstaking work and proclaim—the word 
is used advisedly—little shell differences the 
conchologist often passes over. We would 
seriously ask the collector to examine the 
internal aspect of one of the valves of 
a Zebra Mussel, and then compare it with 
the accompanying drawing and see if this is 
not so; a. ad. being the anterior adductor 
scar; ~. ad. posterior adductor scar; f. 7. 
byssal 
] pit. . 
e treatment of the shell terms, LUNATE, ROUNDED, and 
TRANSVERSE by the author, under the heading of ‘ Apertures of 
nivalves,’ are good specimens of the method of a late 
in the work; they need no comment :— 
LuNATE, when semi-lunar or semi-circular, 
as in Hyalinia — Se rap.). 
—Example: Hyalinia lucida (Drap.) slightly enlarged, Torquay. 
ROUNDED, wise not perfectly round, owing 
to the interruption of the penwipmate whorl, as 
in Helix — Mill. 
ig. 78.—Example : Helix pulchella Miller x8, Kennington, Berkshire. 
Naturalist, 
