PLATE X. 



Fig. 1. — The contrast in this photograpli is more nearly wliat it should he, 

 thon;j;h the haekj^nmnd is in general too liright. Some well-tlelined examples t)f 

 hright hydnigen tioeeuli may he seen to the west of the spot, where small spots 

 were developing at the time. 



Fig. 2. — The contrast here is rather too great, and for this reason the hack- 

 ground appears too dark. The general character of the hright calcium tlocculi 

 is nevertheless fairly well shown. The bright tongue extending into the small 

 spot on the left is erui)tive in character, and con'esi)onds with the hright hydro- 

 gen flocculus referred to in the description of tig. 1. 



155 



