(15c) 



Figure 5. 

 Graphs showing the percentage distribution of spine numbers 

 in lines 9, 30, 41 and 43. 



36 

 33 

 30 

 27 

 24 

 21 

 18 

 15 

 12 



Lines 9 and 41. The ordinates are percentages, the 

 abscissae numbers of spines. 



Line 9- full line. 



Line 41- broken line. 



