
MOLLUSCS, VERMES AND HYDROZOA 

U. complanatus, Fig. 184, is the widely distributed species, found in 
ponds and streams. The valves vary in form but are usually oblong-ovate, 
rather compressed and posteriorally the broader. The umbones are mostly 
eroded and have an obtuse 
ridge to the posterior tip. 
The hinge has a_ single 
coarsely-striated cardinal 
tooth in the right and two 
nearly equal teeth in the 
left valves. Ihe ‘color 1s 
usually a yellowish-green in 

the younger and_ brownish- 
green in the older shells, FIG. 184. Unio complanatus. Adult, 
and is dark green posteriorally at the hinge. The lines of growth are faintly 
and evenly marked. The valves have an iridescent violet pearly nacre 
on the inner side with a delicate pink and salmon-yellow edge, and are 3 
inches long, 2 inches broad and 1 inch thick at the unbones. The animal 
is yellowish-and greyish-white with a long foot. It occurs in almost every 
stream and river on the Atlantic slope and is a most active mussel, often 
moving several inches in a day. A good and desirable scavenger in the 
aquarium where it will often survive for years. 
Lampsitis. This genus of the Unionide was formerly classed with 
the Unios and embraces most of the Eastern and Middle States species. 
L. radiatum, Fig. 185, has broad oblong-ovate beautifully striated dull 
greenish-yellow valves showing distinct lines of growth and overlaid with 
green and brown rays radiating from the edges of the umbones. It is one 
of the handsomest fresh- 
water mussels. Theinterior 
of the valves shows a deli- 
cate iridescent nacre and 
the hinge has erect cardinal 
teeth strengthened by a rib 
behind the anterior mus- 
cularimpression. It grows 
to a length of 3 inches, 
nearly 2 inches broad and 
114 inch thick; and may be found in most large ponds and streams, but 
is not as long-lived in the aquarium as the foregoing. 
L. ochraceus, Fig. 186, is variable in form but usually has thin, trans- 
versely oblong, sub-ovate, translucent, inflated and widely gaping valves, 
with elevated and almost touching umbones. The color is yellowish- 

242 
