MUSSELS AND PECTENS 



39 



Crenella decussata^ Montagu, the Netted Crenella, 

 is a little affair, about 3 mm. long, which is circum- 

 boreal in its range. The valves are rounded and 

 marked by numerous radiating ribs. The edge of the 

 shell is crenulated behind the ligament area. While 

 it is sometimes found in San Pedro Bay its true home 

 is in the north, where several allied species are also 

 found. 



The Pectens, or 

 Scallop-shells, 

 are among the 

 most pleasing 

 mollusks to be 

 found in the 

 ocean. Of regu- 

 lar shape, bright- 

 ly colored and 

 finely sculptured, 

 it is no wonder 

 that their shells 

 have been imita- 

 ted in all sorts of 

 carved work. And 



it one is fortunate enough to become acquainted with 

 a live specimen, he will be abundantly rewarded by 

 watching its interesting habits. We have a good 

 many species on this coast, some of which are not 

 too distinct from one another. 



The first in importance is Pecten circularise var. 

 aequisi/lcatus^ Cpr., the Speckled Pecten, a good view 

 of which is given in Figure 19. This species abounds 

 in the south, where it may be dredged in large 



Fig. 19 



