142 



GEODIA AGASSIZIT. 



of this group examined in respect to the fifteen spicule-dimensions under dis- 

 cussion. From the fifteen points forming this Hne of mean general averages, 

 the numbers in VI, giving the deviations from the means in a commensurate 

 manner were plotted on their respective ordinates, — above if positive and below 

 if negative — and designated with the letters A — I standing for the lots from 

 the nine different stations. The points with the same letter, commensurately 

 representing the different dimensions of the spicules of the same lot, were then 

 connected by lines. The nine lines (curves) thus obtained are maximum spic- 

 ule-dimension curves and graphically represent the peculiarities of each of the 

 nine lots in respect to the fifteen spicule-dimensions selected. 



The nine stations where these sponges were collected are situated on the 

 Pacific coast of North America, between 33° and 56° N. They are not uniformly 

 distributed but form five groups separated by wide intervals, and thus these 

 sponges may be said to come from five distinct regions. These are, from north 

 to south: 1. Behm Canal Station (4228, H); 2. Vancouver Island Stations 

 (4193, 4199, F. G.); 3. South Oregon Stations (2886, 2887, 3088, A. B. D.); 

 4. Middle California Stations (3168, 4551, E. I.); and 5. South Cahfornia 

 Station (2978 C). 



The spicule-curves. Figure F, pertaining to the lots from these five different 



regions are differently drawn as follows: Behm Canal (H, 4228) ; 



Charlotte Sound and Gulf of Georgia (F, G, 4193, 4199) -; coast 



of southern Oregon (A, B, D, 2886, 2887, 3088) ; coast of middle 



Cahfornia (E, I, 3168, 4551) ; and coast of southern California 



(C, 2978) 



