100 THE NAUTILUS. 
the posterior margin in P. compressum is rounded or flattened, it is 
sharp, somewhat “ pinched ” in P. punctatum. In this the shell is 
purely whitish, or light straw colored, the latter more so when dry, 
while the mature P. compressum is always more or less grayish. <A 
marked feature is the finely and densely pitted interior surface of the 
shell, the dots being distinctly perceptible through the shell from the 
outside. Yet thisis not unique, as I have also seen it in other Pisidia. 
Some specimens show not a trace of the appendages on the beaks, 
yet they are evidently identical. 
In the Tuscarawas River this Pisidium appears to be rare, as 
only thirty were taken, twelve of them in one place, in company of 
about five hundred P. campressum, most of the latter quite young 
to half grown, P. cruciatum and a few P. abditum, which is common 
in pools and ditches. More frequent it is in the Bear Run, where 
about 120 were collected, but only one-fourth of them adult. Those 
from the spring brook mentioned above, are somewhat larger, aver- 
aging 2:0 millimeters long. 
These two well characterized and very small Pisidia are a valua- 
ble addition to our molluscan fauna. Besides them there are several 
other undescribed species from our country at hand. These small 
mussels have been somewhat neglected and a more assiduous col- 
lecting and closer study will doubtless bring to light not only more 
unknown forms, but also interesting geographical relations. 
New Philadelphia, Ohio, Noy., 1894. 
HAMINEA VIRESCENS. (PI. II, fig. 15), 
BY MRS. M. F. BRADSHAW. 
One afternoon in August, when the low tide of the month occur- 
red, we went to our favorite reef of rocks to see what of interest new 
or old we could find. 
There were acres of mussels with Purpura saxicola in great num- 
bers and various colors wedged in between them. ‘These Purpuras 
are graceful in form and often beautifully colored and striped, and 
I never tire of them. There were several species of Acmcea and 
Fissurella voleano plentiful enough, and as we reached the outside of 
the reef where the waves dashed at us threateningly, we found a 
few small Haliotis cracherodii, some seaurchins and starfish. These: 
