COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 107 



2. Shell opaque 



3. Disks without sculpture (interspaces concentrically lamel- 

 lose in juvenile stage only) 



4. Beak closer to anterior margin ; posterior auricles longer 

 than anterior ; obliquity pronounced ; shell rather thick ; 



no central ridges in interspaces 



tumbezensis (d'Orbigny) 



(Gulf of California to Paita, Peru) 



4. Beak at or very near center of shell ; auricles of nearly 

 equal length ; obliquity slight, if any ; shell rather thin ; 

 central ridges almost always present in interspaces 



palmeri (Dall) 



(Gulf of California only) 



3. Disks with sculpture (lamellose or imbricate) 



5. Posterior auricles sharply pointed 



6. Posterior auricles produced to or beyond margins of 

 disks; adult altitude averaging 20 mm; 12-16 ribs 



latiaurata (Conrad) 



(Point Reyes, California to Cape San Lucas, Lower 

 California; southern Gulf of California) 

 6. Posterior auricles not produced to margins of disks ; 

 occasionally every third rib or pair of ribs on left 

 valve higher; maximum altitude 9 mm; 12-13 ribs 

 . velero biolleyi (Hertlein & Strong) 

 (Punta Abreojos, western Lower California to La 

 Libertad, Ecuador) 

 5. Posterior auricles not sharply pointed (their lateral 

 margins nearly right angle to hinge) ; each third rib on 

 left valve higher; central riblet in most interspaces of 

 right valve; maximum altitude 13 mm; 16 ribs 



velero (Hertlein) 



(Las Animas Bay, Gulf of California to Puna, Gulf 

 of Guayaquil, Ecuador) 



Chlamys (Leptopecten) latiaurata (Conrad) 1837 



Plate 35, fig. 1 



Pecten latiauratus Conrad, 1837, p. 238, pi. 18, fig. 9. "Inhabits below 



the efflux of the tide near Sta. Diego and Sta. Barbara." 

 \non] Pecten lati-auratus Conrad. Sowerby, 1842, p. 57, pi. 12, figs. 



