21 3 
PHOLAS ? compressa. 
TAB. DCIII. 
Spec. Char. Transversely obovate, compressed; 
sides deeper than the middle ; extremities 
gaping ; along the middle of one valve is a 
rounded ridge,, and a corresponding furrow in 
the other ; surface marked with many sharp 
concentric ridges crossed by eight or ten 
others,, equally sharp, upon the anterior side. 
The base is rather angular, the ridges thin, distant, bent 
in the middle of the valve ; the whole surface is longi- 
tudinally striated. 
An intermediate shell between Pholas Candida and P, 
crispata, since the valves gape at the sides but have no 
sinus in the margin : in its flattened form and prominent 
beaks it differs from all the species of Pholas we are ac- 
quainted with ; it is not without some hesitation there- 
fore that we place it under that genus . 
The specimen is a cast of the inside of the shell ; it was 
broken out of an indurated Marl nodule found in the 
Kimmeridge Clay upon Shotover Hill by our valued 
friend G. E. Smith, Esq. 
We take this opportunity to acknowledge an error in 
the description of Pholas priscus, p. 158. where we ob- 
serve u the genus Pholas was unknown;” forgetting that 
M. des Hayes had described several species from the 
Paris Basin. 
