FOSSIL CROSSOPTERYGIANS ISI 
the caudal. In these forms a number of paired gular 
plates may occur. 
In a closely related genus, Lusthenopteron, also of 
Fig. 151 
is eae 
ha ¥s 
ity? 
Fig. 151.— Gyroptychius. xX}. Old Red Sandstone, Scotland. (After SMITH 
WoopwarbD.) 
Fig. 152.— Osteolepis. x }. Old Red Sandstone, Scotland. (Restoration 
from SMITH WOODWARD, after PANDER.) 
Devonian age (Fig. 154, A, #), the structure of the basal 
parts of the unpaired fins is exceedingly interesting ; the 
radial supports are unfused, while the basals, merged in a 
Fig. 153. — Holoptychius andersoni, Old Red Sandstone, Scotland. 
single plate, have come into especial relation with the 
axial skeleton ; the subsequent stage of their differentia- 
