GEODIA AGASSIZII. 



141 



pressed by these numbers also graphically. This graph, Figure F, was obtained 

 by erecting fifteen ordinates, representing the fifteen spicule-dimensions under 

 discussion, at equal intervals on a baseline. These ordinates are arranged in the 

 order of the maximum variations of the dimensions they represent, the one to 

 the left representing the most constant dimension. The mean general averages 

 (II) multiplied by the corresponding numbers in III of course all gave products 

 of 100 mm. The points graphically representing these numbers, plotted on 

 the fifteen coordinates 100 mm. from the axis, all lie in the straight horizon- 

 tal line m. This line graphically represents the ideal mean of all the sponges 



