FISHES OF MONTE BOLCA AND NAPLES. 123 
tiire of carbonic acid, or sulphuretted hydrogen 
gas, or of bituminous or earthy matter in the 
form of mud. 
The circumstances under which the fossil 
fishes are found at Monte Boica seem to indicate 
that they perished suddenly on arriving at a 
part of the then existing seas, which was ren- 
dered noxious by the volcanic agency, of which 
the adjacent basaltic rocks afford abundant evi- 
dence. The skeletons of these fish lie parallel 
to the laminae of the strata of the calcareous 
slate ; they are always entire, and so closely 
packed on one another, that many individuals 
are often contained in a single block. The 
thousands of specimens which are dispersed 
over the cabinets of Europe, have nearly all 
been taken from one quarry. All these fishes 
must have died suddenly on this fatal spot, and 
have been speedily buried in the calcareous 
sediment then in the course of deposition. From 
the fact that certain individuals have even pre- 
served traces of colour upon their skin, we are 
certain that they were entombed before decom- 
position of their soft parts had taken place."^ 
* The celebrated fish (Blochius longirostris) from this quarry, 
described as petrified in the act of swallowing another fish (Ithi- 
olitologia Veronese, Tab. XII.) has been ascertained by M. 
Agassiz to be a deception, arising from the accidental juxta- 
position of two fishes. The size of the head of the smaller fish 
supposed to be swallowed, is such as never could have entered 
the diminutive stomach of the putative glutton ; moreover it does 
not enter within the margin of its jaws. 
