SYNONYMY AND SHELL. 
19 
other’s labours, from a personal conviction of the unsuitability of 
the name previously applied, or, from a misapprehension of specific 
characters, which leads them to confuse one species with another, and 
therefore apply theii- names incorrectly; thus Draparnaud mistook the 
French form of Heliv aintkma for Helix cartuidana and thereui)on, 
in the belief that the shell was new to science, described the true 
cartusiana as Helix carthusianella ; the synonymy of the two species 
ill reference to this illustrative incident is shown as follows : — 
Helix eantimm Mont. j Helix cartusiana Miill. 
Helix carthusiana \)Ya.\). ho» Miill. ! Helix carthusianella 
The variability and wide dispersal of Limncea pereejra, and conse- 
quently the protean forms assumed under different conditions of 
e.xistence by this variable and mobile species, have led to its various 
modifications being designated by very numerous names intended to 
denote in the opinion of their authors either specific or varietal 
differences. For this species alone over three hundred names have 
been catalogued, all specifically synonymous, and the great bulk of 
the names applied varietally must also be of the same character and 
refer to modifications previously discriminated and named. 
Probably these evils will never be entirely overcome, and it will 
therefore be a continual task to investigate and place in the 
synonymy of the approiiriate species the duplicate or incorrect 
names bestowed or wrongly used from time to time. These 
incorrectly applied and duplicate names are termed Synonyms. 
Some of these names, though ajiplied to species already discrimi- 
nated and named, may rejiresent strongly marked geographical or 
zoological variations, and as indicating such are worthy of retention 
in the varietal nomenclature. 
Shell. 
Tlie great majority of mollusks have an external covering or shell, 
which is acknowledged to be so characteristic a feature in the group, 
that the term Te.stacea (from testa a shell), has been very appro- 
priately applied to them. One distinguished scientist. Prof. Ray 
Lankester, has even imoposed the application of the term Conchifera, 
or shell-bearing, to the whole of the Mollusca, a name previously 
restricted to the Lamellibranchs. Although the internal oigans of 
the animal often exhibit more important and permanent characters, 
yet the close and intimate connection existing between the animal 
