189 
UNIO porrectus. 
TAB. DXCIV.—fig. 1. 
Spec. Cuar. Subcylindrical, rather compressed, 
above twice as wide as long; anterior side 
very small, the other pointed. 
Tus is the largest species of Unio found in the Sand- 
stone of Tilgate Forest: it is distinguished by its regu- 
larly convex surface and pointed posterior extremity. 
UNIO compressus. 
TAB. DXCIV.—fig. 2. 
Spec. Cuar. Ovate, compressed ; hinge-line bent; 
beaks rather prominent ; lateral ridge square. 
Leneru and breadth in the proportion of 2 to 3: the 
hinge slope is flattened, so as to make the ridges that 
bound it square. The anterior side is as large as in the 
preceding species, although the other is much less. 
A rare species, from Tilgate Forest. 
