Pvn H,i I'UitlS

378 TELLINIDJ5.
fold being less deep in the latter form : Searles Wood,
however, shows,
in his '
Crag Mollusca/
that the extent
of this mark depends on the comparative tumidity of
the shell in many species of Tellina and allied genera.
The last-named author has properly adopted the spe-
cific name balthica. It was at one time said that all
geographical or local names are objectionable ; and
entertaining this opinion I even went the length of
substituting fresh names whenever they occurred in the
List of British Pulmonobranchous Mollusca, published in
the c Transactions of the Linnean Society/ But that
was more than thirty years ago ;
and I have since been
convinced that the objection to all such names is not
tenable. The Committee appointed by the British
Association to consider the subject of Zoological nomen-
clature did not even recommend that they should be
entirely discontinued in future. In the present instance
the word balthica is not only correct, but com-
memorative of the original discovery and of the habitable
conditions which belong to the species. Although it
does not tell the whole truth, there is no falsehood in-
volved in the use of it, nor can it mislead any one. The
size of my largest specimens from open bays, where the
sea-water has the usual degree of saltness, is an inch in
length and one and a quarter
in breadth. Clark ex-
pressed an opinion that the animal " differs greatly
from the typical Tellina in the branchial plate and cha-
racter of the palpi, and thick obtuse foot." Morch has
referred this species to the genus Macoma (according to
Gray Macroma)
of Leach.
Da Costa gave it the appropriate specific name of
rubra ;
and besides being the T. solidula of Pulteney, it
is the T. carnaria of Pennant (but not of Linne), Psam-
mobia fusca of Say, and has four or five other lessknown
names.