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continuous or not (as they really seem to be) the similarity 
of lithological structure of these ichthyolite breccias tends 
to shew the uniformity of conditions over large areas. It is 
more difficult to explain the cause of the accumulation 
and destruction of so many fish and lizards over a large 
extent of sea bottom at the same time. Some Geologists 
attribute the sudden destruction of animal life (as it no 
doubt was in many cases) to noxious gases emitted by 
submarine volcanoes, and it may perhaps have been so in 
this instance. The action of strong and variable currents is 
attested by the rolled quartz and other pebbles, (often form- 
ing conglomerates intermingled with bone) previously men- 
tioned, and the comminuted condition of the animal remains, 
which must have been present in enormous quantities, and 
were evidently deposited in masses at the bottom of the sea, 
and cemented together by iron pyrites in thin layers. It has 
been already stated that these osseous conglomerates whenever 
they have been as yet recognised, always occur at the close 
of one formation and the commencement of another, and it is 
just then that we have often a marked difference in the fauna 
and flora, and in the mineral conditions of the two epochs 
and it is evident that the chemical and mechanical change, 
whatever it was, must have largely affected the marine fauna, 
and may have partly brought about the sudden destruction 
of the animals whose remains constitute the ‘bone bed.’ 
Some years ago, an account was published of a similar 
formation having been discovered by dredging at the bottom 
of the sea, where extensive accumulations of the remains of 
fish were noticed, consisting chiefly of broken bones, teeth, 
and scales, spread over a considerable space both in length 
and breadth, thus constituting a modern ‘bone bed,’ and 
illustrating some of those described in this paper. It is fair 
