CO^CHYLW—DITHYRA. 38. 167 



Shell about half an inch long, and rather more in breadth, of 

 a pale rufous color with darker oblique bands, rounded at one 

 end and somewhat angular at the other, strongly striate longi- 

 tudinally and crossed ivith finer lines: beaks near one end, very 

 remote from each other, incurved, with a broad smooth space 

 between them ; the upper margin sinuous and gaping in the 

 middle ; inside whitish or tinged with chocolate-brown. 



Arca testd oblongu decussatu, antice angulatd, margine supero '"sea. 



transcersiin hreviori recto stihciauso. 

 Shell oblong decussate, angular at the anterior side, with tlie 



upper margin shorter straight and nearly closed. 

 Arcafusca. Donovan, v. tab. 158, fig 3, 4. 



Blontagu, Suppl. p. 51, tab. 4, fig. 3. 



Pennant, Brit. Zool. iv. p. 215. 



Turton, Conch. Diet. p. 10. 

 Arca imbricafa, Dillwijn, Descript. Catal. p. 226. 

 Arca Noa;, \ ar. Chemnitz, vii. p. 183, tab. 54, fig. 532. 

 Balanus Bellonii. Lister, Conch, tab. 367, fig. 207. 

 Western coasts. 



Shell resembling the last species, but is narrower in proportion 

 to its length, in consequence of the upper angle being shorter 

 than the lower ; it is also more convex, with finer decussations, 

 and the margin is nearly straight : the beaks are very remote, 

 and it wants the oblique zigzag bands. 



Arca testa rhoinhed granvloso-decussatd, cosld obliqtiu (ctrajrona. 

 longiludinali, margine hiante. ' 



