96 TURTONIAD. 
then by the retractor muscle itis drawn forward, making such 
rapid progression as to cross a watch-glass in a minute, and on 
the passage turns itself several times by a twist of the foot 
from side to side. No siphonal processes, nor even a simple 
orifice, were observed. When opened, the large foot is the 
most prominent object ; with a good lens the byssal fissure is 
distinctly visible. Though there are traces of a branchial 
lamina, we could not detect its configuration, nor the presence 
of palpi. In the hinge, under the beaks, there is a minute 
obsolete primary tooth or two, with only a single compressed 
triangular lateral, in both valves, but on the longer side only, 
which is the anterior one. This structure differs much from 
Kellia. 
Some malacologists call what we term the lateral teeth in 
Kellia and this genus, the cardinal ones ; but as in them there 
is no moveable ossicle, we consider the minute denticles at the 
edge of the cartilage-pit, directly under the beaks, the primary 
ones. But the case is different in those minute species styled 
by authors Montacuta bidentata and M. ferruginosa; these 
have been removed by us to the Anatine, as they have the 
characteristic ossicle of the family; in them there are no 
minute cardinal teeth, and what in Kellia and Montacuta are 
termed laterals, here become of cardinal value. 
TURTONIADA, Clark. 
We have been obliged to establish this family for Turtonia, 
with a single genus of only one species, planted by authors in 
the Kelliade, though it has not the shghtest community of 
attributes or structure with any of the genera of that group. 
Lepton, Galeomma, Kellia and Montacuta are as far asunder 
from it as the poles. We mention a convincing proof of its 
heterogeneity : in all the species of those genera, excepting 
perhaps Kellia suborbicularis, im which the sides are nearly 
equal, the shortest is the posterior one; but im Turtonia 
minuta the longest is posterior, and it is the only animal of 
these tribes that has a considerably produced anal siphon. 
a 
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