PLATE XVI. 



Tlie photoiiiaiih reprodiu-pd in this plate reprosents tlio medium level flocculi 

 siirroiuuliiii: the spot jii-oup. as th(•.^ appeared on October 10. 'IMie chaiii^es in 

 the group may be seen by eomi)aring this photogrpah with Plates XIII-XIV. 



SM 1904 11 l<il 



