38 
PHOLADOMYA virgulosa. 
TAB. DC XXX.— Jig. 1. 
Spec. Char. Transversely elongated, convex, rib- 
bed ; ribs numerous (about 24), rounded, thin, 
crossed by many irregular waves, obscure on 
the anterior and wanting on the posterior. slope ; 
beaks near the anterior extremity, which is 
truncate ; section ovato cuneiform. 
At least one-fourth wider than long, with the sides a little 
flattened ; the ribs above 24, thin, and divided into small 
tubercles by the concentric undulations. This shell has 
long been known as found in the Bognor rocks, but I am 
not aware that it has been discovered elsewhere. The 
name has been given it by a society of gentlemen who meet 
to study tertiary fossils. It is a very distinct species ; the 
specimen figured is in Mr. Dixon’s cabinet. 
PHOLADOMYA Dixoni. 
TAB. DCXXX.— -fig. 2. 
Spec. Char. Transversely oblong, gibbose, rib- 
bed along the middle, concentrically waved ; 
ribs few (about 12), slender ; beaks large, 
placed neartthe truncated but not gaping an- 
