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salts as gypsum and rock salt, from which the outflowing water extracts its 
saline contents. Or the saline constituents may he dissolved from other 
strata by the water before reaching the mud-volcanoes, and left behind in 
the dry mud, upon the evaporation of the water. 
The mode of distribution of mud- volcanoes shows a certain general rela- 
tion to volcanic regions, and volcanic eruptions. They are, however, found 
in countries at present unaffected by volcanic phenomena, but in this case 
they either occur in districts which are frequently disturbed by upheavals, 
and sinkings, or are confined to tracts of great geotectonic fissures and lines 
of displacement, which traverse the crust of the earth, and lead down to. 
great depths. 
From all these facts Professor Giimbel thinks it follows that the true 
focus of the phenomena connected with by far the greater number of mud- 
volcanoes cannot be directly identified with that of the volcanic activity of 
the depths of the earth, but that these phenomena are due rather to the 
presence of certain stratified rocks, and to their containing intermixtures 
capable of furnishing bituminous substances. In isolated cases it may be 
that gases connected with volcanic processes produce phenomena similar to 
those of ordinary mud-volcanoes, or associate themselves with the carbu- 
retted hydrogen gases of the true mud-volcanoes, just as, vice versa, the latter 
gases frequently appear among volcanic exhalations. The stratified rocks 
involved in the process, must be situated deep in the earth’s crust, where the 
conditions (warmth, &c.) necessary for the evolution of the gases and 
bituminous materials from the organic intermixtures are present, and at the- 
same time the crust of the earth is traversed by fissures deep enough to 
enable the volatile materials thus formed under pressure to make their way 
to the surface. Such favourable conditions will occur most frequently where 
the younger sedimentary formations are deeply buried, and traversed by 
deep fissures by volcanic action. In this way we see how the phenomena 
of mud-volcanoes are distantly connected with true volcanic activity. In 
other cases, volcanic action may as, it were, have carried the conditions of 
formation of the eruptive gases and bituminous substances nearer to the sur- 
face, and into the higher beds of the sedimentary rock. Such a relation 
between mud-volcanoes and vulcanicity may be assumed especially in Sicily. 
Nevertheless, the phenomena of the so-called mud-volcanoes are so funda- 
mentally distinct from those of true vulcanicity, that it seems desirable to 
get rid of the connection, apparently implied by the name, by the employ- 
ment of a new term, such as “ mud-springs ” ( Schlammsprudel ). 
Palceocoryne. Mr. G. It. Vine read a communication before the Geological 
Section of the British Association, in which, after referring to the great 
abundance of Carboniferous Polyzoa which have been discovered of late 
years, he gave the results of his researches upon the curious fossil bodies 
described by Professor Duncan and Mr. Jenkins, as probably fossil Hydroids, 
under the name of Palceocoryne. These supposed Hydroids have been re- 
garded by some palaeontologists, and notably by Dr. and Mr. Young of 
Glasgow, as mere appendages of Polyzoa. The author stated that he had 
identified all the species and forms of Palceocoryne that had been figured by 
Dr. Duncan in his various papers ; but the conclusion he had arrived at was 
that these so-called organisms were neither hydroid, as was supposed by 
