RHODOPHYCEA, OR FLORIDEA 243 
doubt in the Senonian beds (near the top of the Cre- 
taceous beds) as Lithothamnion, and are thus of the 
same proved antiquity as the Diatoms. It does not 
occur massively until the Tertiary rocks are reached, 
aes 
SEEN 
SN 
Fic. 84.—Corallina mediterranea, vertical section through antheridium 
highly magnified. (After Thuret and Bornet.) 
when this contemporary genus occurs abundantly in 
the lower Eocene. The Leitha limestone (Miocene), 
the Pisolite limestone, and the nummulitic rocks, 
are largely composed of Lathothamnton. 
Though of greater abundance in warm tropical 
R 2 
