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PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. .May 26,
was unknown to M. Pictet at the time he published his work, I
here append the drawings I made in 1848 from specimens formerly
in the possession of the late M. Bouchard, which had been sent to
Fig. 1. — Terebratula diphyoides.
him by M. Malbos, from the compact limestone of Berrias (Ardeche).
I never could »see the necessity of burdening nomenclature by the
adoption of a distinct generic denomination for these shells ; and we
should not be zoologically warranted in supposing that because the
mantle or lateral portions of the valves have been more or less pro-
longed, we have therefore valid grounds for the creation of a new
genus, any more than we are warranted in separating Orthis hiloba,
Linn., from the Genus Orthis because the lateral portions of the
valves are more or less prolonged in a similar manner to what we
find in the deviating lobes of the valves in certain specimens of T.
diphyoides, T. viator, etc.
It is very interesting to know that Mr. E. Tawney has discovered
a Diphyoid Terebratula in a block of Oxfordian age" in the Canton
de Vaud, and it is most probable that the shell is referable to T.
viator ; but in that case it would be very necessary that the true age
of the block in question should be accurately determined, so as to
feel certain that it also might not pertain to the age of the limestone
of the Porte-de-France. Nor must it be forgotten that M. Alphonse
Favre found a similar specimen at Yoisons, near Geneva, which is