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 JN'orth 

 American localities. During the Devonian era it existed in several 

 parts of Devonshire, in France, and G-ermany. 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 Jiemisphcdrica seems 

 not to have begua life quite so early as its friend which we have just 

 dismissed ; its origin dates in Tipper 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 "perfoliatwm differs 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 Hams- 

 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 Favosifes 

 Goldfussi occurs in Devonian rocks in Devonshire, at Nehou and 

 Vise in Trance, 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 Pauna 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 with such 

 conclusions. ChonophiiUum perfoliafHin formed part of the Silurian 

 and Devonian Faunas, but was confined to the British area ; Favosites 

 Goldfussi was at liome 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 



