TRANSACTIONS OF THE SECTIONS. 95 



It must be understood that any one of the ten columns just noticed shows, not the 

 total number of species common to the areas the initials of which stand at its head, 

 but simply the number at once common and restricted to them collectively; thus the 

 second of these columns, headed L. S. D., L. C, shows that five species are common 

 and restricted to Lower South Devon and Lower Cornwall ; but in the third column 

 we find one species common to them and also to Lower North Devon, in the fourth 

 one common to them and to Upper North Devon, and in the eighth one found in each 

 of them and also in Upper North Devon and Upper Cornwall; hence there are eight 

 species common to the two areas instanced, five being restricted to them collectively 

 and three not. The same explanation applies to the other areas. Hence the total 

 number of species found in any area will be ascertained by adding the figures in all 

 the columns marked "Peculiar to" and "Common to" at the head of which the 

 initials of the area are found ; thus, for example, a total of 47 species of .Zoophyta 

 occurs in Lower South Devon, of which 40 are not found elsewhere in Devon and 

 Cornwall. Moreover, as the column marked " Species " shows that the two counties 

 have yielded a total of 49 species belonging to this class, it is evident that two of this 

 total number have not been met with in Lower South Devon. And so on for the 

 other classes and areas, as is shown in the five columns headed " Totals " and 

 distinguished by the initials of the areas. 



Of the 347 species, 67 are met with in various parts of Continental Europe, and 

 7 in North America; G of the latter being included in the European 67, and one of 

 the 6 is also found in New South Wales; thus making a total of 68 common to Devon 

 and Cornwall and to districts beyond the British Isles*. 



Comparatively few of the Devonian fossils of the two counties appear to have been 

 derived from the Silurian fauna ; eight species only are referable to that earlier period f. 

 Amongst these are the three corals, Favosites fibrosa, Emmonsia hemisphcerica, and 

 Chonophijllum perfoliation. The first has been found in Lower Silurian rocks at 

 Llandovery; in the upper 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 in Germany. The second, Emmonsia hemisphcerica, dates its origin 

 in Upper Silurian times, when it seems to have been confined to the area of modern 

 North 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. 



Clionophyllnm perfolialum differs from the two former in having always lived 

 within narrow geographical limits ; it occurs in Upper Silurian beds at Wenlock, and 

 in Devonian in one quarry near Newton in Devonshire; but its appearance is not 

 recorded elsewhere. 



The wide geographical range of the first two would seem to imply hardy plastic 

 constitutions, fitting them for distant travel, and existence under varied circumstances; 

 there is, therefore, nothing very surprising in their extended vertical range ; it is, 

 perhaps, worthy of remark, that the second seems to have disappeared 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 physical 

 and thermal changes such as, there are reasons for believing, considerable lapses of 

 time have always introduced into any given area; changes probably similar to those 

 which an organism would experience 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 Devo- 

 nian rocks in Devonshire, at Nehou and Vise in France, at Millar in Spain, in the 

 Oural, in the States of Ohio and Kentucky in North America, and in New South 

 Wales. It seems to have successfully struggled with the varying conditions of change 

 of place, and might have been expected to be equally capable of contending with 

 such as depend on lapses of time ; nevertheless, the facts do not harmonise with such 



* See in Table I. the columns headed Eu. (Continental Europe), Eu. Am. (Europe and 

 America), Am. (America), Eu. Am. Au. (Europe, America, and Australia), 

 f See in Table I. the column headed " Silurian." 



