247 



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...H. Scotland. I believe this shell is the 

 C. Garensis of some writers. The C. Multicast ata of 

 Macgillivray is our Compressa. 



C. Svi.CATA.Maca. 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 

 Danmoniensis, but in that shell the ridges are much 

 narrower than the furrows. 



C. (Astarte) 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 oblong impression ; 

 posterior slope nearly straight to the end of the oblong 

 impression; valves moderately thick with irregular 

 flattened concentric ridges and shallow sulci oblite- 



