scarcely elevated concentric ribs which become obsolete 
at the sides and are, as well as the interstices, concen- 
trically striated ; cuticle light yellowish-brown : margin 
entire. 1...13. Scotland. TI believe this shell is the 
C. Garensis of some writers. The C. Multicostata of 
Macgillivray is our Compressa. 
C. Suucata.Macg. Aberd. 229. (not his synonyms) 
Rounded-triangular, subangulated anteriorly, convex ; 
posteriorly longer; umbones pointed and contiguous ; 
dorsal slope convex. the impression lanceolate ; posterior 
slope somewhat concave, lunule ovate-lanceolate ; valves 
very thick, with twenty five or more concentric ridges 
of the same breadth as the interstices, which as well 
as they,are concentrically striated ; cuticle olive brown, 
margin crenated. 0,8...1. Aberdeen. Very like 
Danmonensis, but in that shell the ridges are much 
narrower than the furrows. 
C. (dstarte) Compressa. Macgill p. 261. (not 
Turt.) Ovate-triangular, compressed, posteriorly 
shorter, umbones pointed ; dorsal slope straight for half 
its length, then convex with a linear obleng impression ; 
posterior slope nearly straight to the end of the oblong 
impression ; valves moderately thick with irreguiar 
flattened concentric ridges and shallow sulci oblite- 
