84. R. ETHERIDGE ON MOLLUSCA FROM 
interlocking of the tooth in the left valve at the uppermost part of 
the lunule into that of the right valve*. 
CorBULA CANAMAENSIS, Hther. (PI. VII. figs. 3, 3a.) 
I have no means of determining whether this be a new species or 
not; the forms are so similar, and specifie differences amongst them 
too slight to be observed from figures, unless specimens for compari- 
son are before us. I give it a local geographical name, and figure 
the shell in case other specimens are collected from the same wide 
area; probably this form is estuarine. Corbula (Potamomya) labiata 
(Azara, D’Orb.), from the La Plata, and also from the Pampas and 
other places in the Argentine Republic, may be this species or a 
variety. Although this shell resembles Anisothyris erecta, Conr., and 
the figure by Dr. Bottger, Jahrb. k.-k. geol. Reichsanst. 1878, t. 14. 
f. 12, I still believe it to be quite distinct. 
Joe. Canama. 
TerRacta? 
One valve (left) only of this genus oceurs. Although probably a 
mature shell, it is a small species; no name can be given to it. 
Loc. Canama. 
LurTrartia ? 
Like the above (Thracia); only one valve of some small species 
occurs. Both appear to be marine gerera; but we know not under 
what condition they were deposited or became associated with the 
estuarine and freshwater fossils. I name them with doubt. 
Loc. Canama. 
ANODON, sp. 
Two fragments only testify to the freshwater condition of the 
strata in which they occur. The shell of this species must have 
been thick and large. 
Loc. Cliffs a few miles below Canama. 
Unto. 
We have the anterior portion only of an elongated species. Umbo 
very anterior, eroded, having one large elongated tooth and slightly 
rugose posterior markings; one long posterior hinge-tooth occupies 
more than half the length of the shell. Shell thick, 
Loc. Cliffs a few miles below Canama. 
* Dr. H. Woodward, in his paper upon the Tertiary Shells of the Amazon 
valley, under the genus Pachydon, notices many affinities and differences be- 
tween the above genus and certain allied forms, such as Corbula, Azara, 
Neera, &e. 
