18 
THE GEOLOGIST. 
deposits of the same system in various parts of the typical Silurian 
country, in eight counties of Ireland, in Russia, and in three North 
American localities. During the Devonian era it existed in several 
parts of Devonshire, in France, and Germany. Apparently confined 
to Britain during the earliest stage of its existence, it became more 
adapted to the world, or the world to it, during the Upper Silurian 
age, when it reached the maximum of its migratory powers (by no 
means an ordinary one), and visited many distant parts then ; 
declining in vigour, or satiated with travel, it retired within the 
European borders during the Devonian period, and there received 
its dismissal from the stage of life. Emmonsia }iemispli(Brica seems 
not to have begun life quite so early as its friend which we have just 
dismissed ; its origin dates in Upper Silurian times, when it seems to 
have been confined to the area of modern America, ranging from the 
State of Ohio to Tennessee ; having outlived the Silurian period, it 
sent colonies to Spain and Britain, and greatly extended its range 
in America. Chonophyllum perfoliatum diff"ers from the two former 
in having always lived within narrow geographical limits ; it occurs 
in Upper Silurian rocks at Wenlock, and in Devonian beds at Rams- 
ley, near Newton Abbott ; but its appearance elsewhere is not re- 
corded. 
The wide geographical range of the two first of these corals would 
seem to imply hardy plastic constitutions, fitting them for distant 
travel and existence under varied circumstances ; there is therefore 
nothing surprising in their extended vertical range ; the second, 
however, seems to have disappeared when at the very zenith of its 
"widely extended power. 
The very limited distribution in space of the last of the trio would 
scarcely suggest the thought that such an organism would be likely 
to be capable of enduring thermal and other physical changes such 
as, there are reasons for believing, considerable lapses of time intro- 
duce into any given area, changes probably not dissimilar to those 
experienced in passing to a distant locality in any one and the same 
period. On the other hand, the well-known fossil coral Favosites 
Goldfussi occurs in Devonian rocks in Devonshire, at Nehou and 
Vise in France, at Millar in Spain, in the Oural in Russia, in the 
States of Ohio and Kentucky in North America, and in New South 
Wales ; it was the most decided cosmopolite of the Fauna to which 
it belonged, the greatest traveller of its day, the earliest Devonian 
that circumnavigated the globe, the prototype of the Drake of a later 
age. It seems to have successfully struggled with the varying con- 
ditions consequent upon change of place, and might have been ex- 
pected to be just as capable of contending with such as depend on 
lapses of time ; nevertheless, the facts do not harmonize w ith such 
conclusions. Chonophyllwn perfoliatum formed part of the Silurian 
and Devonian Faunas, but was confined to the British area ; Favosites 
Goldfussi was at home in every part of the world, yet it commenced 
and terminated its career within the Devonian period. 
The rocks of Devon and Cornwall have fifty eight species of fossils 
