PYRAMIDELLID. 403 
cleansed them from every particle of dried animal matter, a 
difficult task from their minuteness ; I have them on tablets, 
and shall be glad to show them to competent observers. 
They are interesting from the fact, that Chemnitzia and 
Jeffreysia are the only marine Gasteropodan genera that have 
these singular processes, except the Barleeia rubra, late the 
Rissoa rubra, which, from its apophysis and testaceous ld, 
has been shown above to be alien to Rissoa. The apophysis 
is nothing more than an extension, sometimes from the 
margin, but more usually, in Chemnitzia, sprmging from the 
under surface, and appears to act as a clamp to strengthen 
the closure of the operculum. ‘This process is strikingly 
conspicuous in Ch. conoidea and Ch. plicata, much more so 
than in Jeffreysia diaphana ; i Ch. acuta it approaches nearly 
to the two latter species, but is not quite so marginal; in Ch. 
spiralis, Ch. decussata, and Ch. interstincta, it scarcely varies 
from Jeffreysia. 
The above generic diagnoses and peculiarities are absolutely 
alike im all the animals of our tribe of Chemnitzie, whatever 
may be the form of the shell: how then can we, at this epoch 
of natural history, fall back upon exclusive and false concho- 
logical indices in the formation of our families and genera, 
such as, for example, the presence or absence of a tooth, the 
smooth or sculptured shell, and thus throw overboard the 
consideration of the soft parts and functional organs? Are 
variations of sculpture and a denticular pomt of almost in- 
organic matter to outvalue the peculiar external organs of 
the animal, as well as those internal ones which are the seat 
of the nerves and of vitality? If these positions are true, 
how can identical creatures be consigned to separate genera ? 
Who will venture to draw a valid animal distinction be- 
tween a Chemnitzia and an Odostomia? If this is impos- 
sible, this smgular tribe, united by so many ties, ought not 
to form two divisions or genera. This is not my fiat; but 
nature, reason, and the fitness of things forbid so unnatural 
a disseverance. 
We thus see that the Chemnitzian animal, by its head para- 
phernalia and cesophagean structure, is a compound one, 
2D2 
