Geology. 419 
and which have lately been accessible owing to the dry men rae 
of micaceous brownish red sandstone and red marls, with true cornstone 
Pterygotus. The fish remains consist of distinct jaws and teeth of con- 
siderable size, of fin defences (Onchus), and the heads of ee 
Lyellii, and a new species; to 
occurs, 
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“tilestones,” if applied either to the top of the upper . 
’ ‘ ight mislead; but if ap- 
base of the Old Red Sandstone exclusively, ™ 6 two deposits, it may 
