NO. 6 OYSTERS OF THE LOPHA LUGUBRIS GROUP — KAUFFMAN 



45 



Table 2. — Summary of measurements for Lopha bellaplicata bellaplicata 

 ( Shumard) — continued 



Character Valve 



Number of primary plicae at first 



appearance 3 



Total number of plicae (plicate ( 

 valves only) — 



At 10 mm. height 1^ 



( 



At 20 mm. height \^ 



At 30 mm. height J^ 



/ R 



At 40 mm. height 1^ 



/ R 



At 50 mm. height \^ 



j R 



Total number of plicae at margin 3 



Number of plicae in 20 mm. length ] L 

 at 20 mm. height ) R 



Percentage increase in plicae by 

 bifurcation J 



Width of posterior auricular sulcus, 

 20 mm. below beak L 



Width of median plica 20 mm. below 



beak L 



Inclination of beak, umbo : 



f T 

 Percent opisthogyre ) 



Percent orthogyre ) 



|r 



Percent prosogyre ) 



( 



Length of hinge line (LHL) J ^ 



/ R 



Ratio, LHL:L jL 



Height of denticulate portion of 

 margins (HD) 3^ 



Number of denticles in 5 mm. distance 

 along margin 3 



Ratio, HD:H J^ 



Maximum diameter of muscle scar 

 (MDS) P- 



m 



Ratio, MDS:H )^ 



R 



53 



.4-9.4 



Average 



10.6 

 13.4 



14 



11.6 



15.8 



14.8 



17.9 



19 



18.4 



15.8 



18 



17.9 



16.4 



15.9 



5.6 



5.9 



79.6% 

 72.1% 



4.9 mm. 



