AIR-BREATHERS fot 
their foot to the upper surface of the water—an 
apparently impossible feat, but they do it never- 
theless. 
They make little nests of transparent jelly, filled 
with minute eggs, and attach them to the side of the 
jar, where you ean easily watch the development of 
the embryos. In my Jar the little things came out 
after twenty days, each with a perfect shell, and 
began life on their own account. Such a jar may 
properly be kept in a schoolroom. 
Physa politissima, Tryon, the Polished Physa, 
is an inhabitant of Oregon. It resembles the last 
species in form, and has a brilliant shell, with a 
dark line near the edge of the outer lip. All of the 
Physas have sinistral shells, and may thereby be 
recognized at the first glance. 
Physa carltoni, Lea, Carlton’s Physa, comes 
from near Antioch, Cal. The body-whorl is full 
and round, horn-colored; outer lip marked inter- 
nally with stripes of dark brown. It is quite large, 
having a length of three-fourths of an ineh. 
Physa gabbi, Tryon, Gabb’s Physa, has a small 
spire, consisting of three or four minute whorls; 
body-whorl large, aperture large also, outer lip 
broad and full. Specimens from. Portland, Ore., 
are light horn-colored, and from half to a whole 
inch in length. 
Physa costata, Newe., the Ribbed Physa, has a 
very small, thin shell, with a somewhat ribbed or 
corrugated surface. From Clear Lake, Cal. 
Physa ampullacea, Gld., the Inflated Physa, has 
a large, full shell thin, shining and. horn-colored. 
