32 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



Table 1. — Summary of measurements on specimens of Lopha lugubris (Conrad) 



Character Valve 



Height (H) J^ 



Length (L) j^ 



Width (W) (^ 



( 



Percent valves with H > L LR 



Percent valves with L>H LR 



Percent valves with H = L LR 



Area, inscribing rectangle of valve 



(HXL) L 



Length, beak to posterior margin 



(LBP) L 



Ratio, LBP:L L 



Angle of inclination (i) \ 



Height of attachment scar (HATS). L 

 Length of attachment scar (LATS) . L 

 Area, inscribing rectangle of attach- 

 ment scar (HATS X LATS) L 



Ratio, area of scar (inscribing rec- 

 tangle) : area of valve (inscrib- 

 ing rectangle) L 



Percentage of valves with plicate 

 exterior surface (not including 

 those with only the margin plicate 

 or crenulate) ) 



Height, smooth young stage (HSS), 

 on dorsal part of plicate valves .... 3 



HSS on left valves with HSS > 

 HATS L 



Ratio, HHS:H j^ 



Number of primary pHcae at first 



appearance \ 



(^ 

 Number of plicae at 10 mm. H (on 



shells where HSS<10 mm.) )^ 



Number of plicae at 20 mm. H ) 



Total number of plicae (marginal 

 count) ) 



Number plicae in 20 mm. L at 

 20 mm. H (median plica central) . .3 



133 



1 18.8-564.0 mm. 272.5 mm. 



100 0.13:1-0.78:1 



0.46:1 



