IX 
also marked by slight contemporaneous erosion, as shown to the right of 
Plate B. Although the shales associated with the Pish-hed arc probably 
partly tuffaceons, it is very improbable, to judge from the remarkable 
evenness and regularity of these strata, that the fish perished through an 
inflow of volcanic mud, or the falling of a shower of volcanic dust. The 
evidence quoted seems rather to favour the supposition that the fish, which 
evidently lived in some land-locked lake or sheltered estuary, where there 
Avas not sufficient current to efface the ripple marks, and where delicate 
plants could he preserved in the fine muds, were killed by the sudden silting 
up of the lake or estuary Avith thick l)eds of coarse sand and gravel SAvept 
doAvn by poAverful floods of fresh AAvater. 
T. W. EDGEWOBTII DAVID. 
llrt 74-90 
C 
