458 MOLLUSCA. 
A very beautiful species, much like P. palium beneath, but re- 
markable for the distant ranges of elevated spines on the alternate 
ribs, the intervening ones being quite depressed, and with merely fine 
squamous strie, like the rest of the surface. 
Figures 570, 570 a, the two sides of the shell; 570 4, edge of the 
shell; 570 c¢, details of sculpture. 
PecTEN CAuRINUS (Gould). 
T. trigono-orlicularis, haud crassa, inequivalvis, sub-equilateralis ; valva 
supertor convexiuscula, rubra, striis concentricis tenuibus insculpta, 
costis humilibus rotundatis vel interdum sub-duplicatis ad viginti 
ornatis: valva inferior convezxa, alba, versus marginem rubricans, 
radus ad viginti-duo elevatis, quadratis, longitrorsum striatis ; nati- 
bus rosacets compressis ; auribus transversis, sub-equalibus, radiatim 
striatis : intus lactea, limbo rosaceo. 
Pecten caurinus, Goutp; Proceed. Boston Soc. Nat. Hist., iii. 345. 
Dec. 1850. Expedition Shells, 95. 
SHELL large, rather thick, nearly circular, a little inequilateral, and 
slightly oblique; the valves unequal; the upper valve is purplish-red, 
slightly convex, marked with delicate lines of growth, and with twenty 
or more slightly raised, rounded ribs, about half as wide as the inter- 
spaces, diminishing towards the sides, and sometimes nearly sub- 
divided by one or more furrows; the lower valve more convex, white, 
and becoming reddish towards margins, and with about twenty-two 
ribs, equal to the interspaces, elevated, flattened at summit, and with the 
sides vertical, and even incumbent; sometimes there are obsolete inter- 
vening ones. ‘The ears are transverse, nearly equal, the anterior ones 
faintly rayed with scattered lire; the sinus broadly rounded; beaks 
roseate, compressed ; interior milk-white, with a silky lustre, and 
roseate marginal limb. 
Length two and three-fourths inches; breadth two and a quarter 
inches; height one inch. 
Obtained at Port Townsend, Admiralty Inlet, Oregon. 
