182 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Semele flavescens Gould, 1851. 
Boston Soc. Nat. Hist., 4:392. 
Shell subrotund, nearly equilateral, moderately convex, anterior end 
broadly rounded; posterior dorsal margin straight and sloping, the end 
less broadly rounded; posterior umbonal slope with an indistinct ridge; 
beaks acute, not prominent, anterior dorsal area excavated; posterior 
dorsal edge long lanceolate, concave, bounded by a distinct angle; surface 
pale orange near the beaks, becoming dingy white at the older stages, and 
covered by a dirty greenish epidermis; marked by concentric lamellar 
striae, crossed by fine radiating striae, especially across the disk. Interior 
tinted melon yellow, spangled with shining dots; siphonal sinus spatu- 
late, veined with numerous diverging striae; ligament pit deep and long; 
anterior lateral teeth approximate to beaks. Longitudinal, vertical, and 
transverse diameters two and three, two and one-eighth and one and 
one-fourth inches. (Gould.) 
Type in Boston Soc. Nat. Hist. Type locality, San Diego, California. 
Range. San Pedro to San Diego, California. 
Genus CUMINGIA Sowerby, 1833. 
Shell transversely oval, equivalve, rounded in front, subrostrated and 
slightly gaping behind, small, thin, often irregular in form; hinge with a 
spoon-shaped cartilage pit, and a small anterior cardinal tooth in each 
valve; two elongate lateral teeth in the right valve, less developed in the 
left; beaks small; surface concentrically ridged; pallial sinus very wide. 
Living in sponges, sand, and in the fissures of rocks. (Tryon. S. S. Conch.) 
Type. Cumingio mutica Sowerby. 
Distribution. West Indies, India, Australia, West America. 
Range in Time. Pleistocene. 
Cumingia lamellosa Sowerby, 1833. 
Proc. Zool. Soc., 1833, p. 34. Conch. Iconica., Cumingia; pi. 1, fig. 2. 
Cum testa ovata, minutissime decussata, antice roundata, postice 
acuminatiuscula; latere postice breviusculo, margine dorsali declivi. Long. 
1.2; lat. 0.5; alt. 0.58 poll. (Sowerby.) 
Shell oblong, regularly concentrically laminated, laminae narrow, stand¬ 
ing out, distant; anterior side short, rounded; posterior side angular, 
acuminated, subrostrated; ventral margin contracted near the end; dorsal 
margin sloped. (Conch. Iconica.) 
Type in British Museum. Type locality, Chile. 
Range. Crescent City, California, to Payta, Peru, and Chile. In the 
Pleistocene at Santa Barbara, San Diego, and San Pedro, California. 
