Neithea wrighti  This species generally ranges fro 42mm x 37mm
x14mm.  The shell is large, subtrigonal, inequilateral,
anterior, and posterior sides of approximately the same length. 
The anterior ear is pointed and prominent, with a transversely
rounded surface.  The posterior ear is rudimentary, and the
ventral margin is sinuous.  The right valve is convex and the
left is almost flat. The right valve also has four prominent
rounded ribs which have a prominent costella at the summit. 
Each valve has a fluted border on the interior side.  This
species is similar to Neithea whitneyi, but this species is more
nearly equilateral, narrower, and more convex.  The ribs of the
Neithea whitneyi are more prominent than those of Neithea
wrighti, having steep sides, whereas those of  Neithea wrighti
have more sloping sides.  This species was found in the
Georgetown Limestone, Austin, Texas.