Paes ee 
=? . _ 
- 
a eee 
VOL. XIV. (2) RH#TIC ROCKS 159 
accumulation of fish-scales and coprolites, and less abun- 
dantly of Acrodus minimus and Saurichthys acuminatus.’ 
These vertebrate remains occasionally appear in the upper- 
most two or three inches of the “green” marls. In places, 
however, they are found in a compact arenaceous rock, 
with small quartz pebbles. Herein too are derived sub- 
angular fragments of the subjacent “green” marl, while 
the contained organic remains are very fragmentary. 
The succeeding deposit of black shales varies in 
thickness from 16 to 24 inches: the usual thickness, 
however, is 16 inches. 
Capping this is a massive bed of calcareous sandstone, 
from 4 to 6 inches thick: it weathers into two main 
layers, the lower being of a “bone-bed” nature. The 
term “micaceous bone-bed” has been suggested; but it 
seems preferable to omit the “micaceous” and to restrict 
the amended term to the true Bone-bed, which has its 
equivalent in most of the Rhetic sections in the west of 
England. The Lamellibranchiata are represented by 
Avicula contorta and Schizodus (“ Pullastra”): in con- 
sequence of the abundance of the latter, local observers 
have denominated the stratum the “Lower Pzdlastra- 
Sandstone.” Vertebrze of fish are somewhat abundant in 
this bed. 
The superincumbent shales are coarsely laminated and 
firm. About the middle of their thickness they contain 
a series of non-calcareous, pyritic, and irregular sand- 
stone layers, exhibiting oblique lamination due to current 
action. 
A stratum of sandstone, similar as regards lithic struc- 
ture to bed 19, succeeds. Moreover, it resembles that 
bed by separating into two main lamine, the lower con- 
taining fish and saurian remains abundantly. This ossifer- 
ous portion occupies the same relative position as the 
1 For the full palzeontological details, see section (Table III.) at end. 
