PELECYPODA—PRIONODESMACEA. 505 



Left valve marked with rounded ribs (slightly keeled at top) and 

 each of the wide interspaces marked with a smaller rib. Right 

 valve marked with squarish ribs, more or less bifurcating ; inter- 

 spaces narrow. 



California, Lower California. 



XCIX. Camptonectes Agassiz. 

 A small, thin Pecten, nearly smooth, more or less inflated, 

 marked with fine, almost microscopic and more or less vermicular 

 groovings which radiate from the umbo and are deflected laterally 

 from a median line on each valve. (This so-called " Camptonectes 

 striation " is common to many recent Pectens both ribbed and 

 smooth.) Valves similarly sculptured. Posterior ear small, 



Fig. 676. Camptonectes bellistriatus. (After Stanton. ) 



obliquely truncate ; anterior much larger, in the right valve cut 



by a deep byssal sinus. Jurassic-Recent. 



388. Pecten (Camptonectes) bellistriatus Meek. (Fig. 676.) 



Jurassic. 



Shell very thin, slightly oblique to the hinge line, compressed. 



Outline subcircular, slightly wider than high. Posterior ear very 



