The Intumescens Fauna. — Clarke. 101 
though preponderating in actual number of species, is a far less 
percentage of the index fossils of the middle Devonian than the 
upper Devonian species there are of typical upper Devonian 
launas. Until quite recently no verj- detailed study of the Tally 
launa had been made, but in a late paper it has been discussed at 
some length b}' Mr. H. S. Williams of Ithaca.* Mr. Williams 
has adduced considerable new data without however elucidating 
the character of the entire fauna as known to-da}'. Conceding 
the well-known fact that the great majority of the species are those 
of the preceding fauna of the Hamilton shales, the author says : 
' ' The fauna of the Tally limestone is made up of two groups of 
species, first those, having closeh' allied forms in the immediately 
preceding middle Devonian formations ; second, those having 
closer affinit}' with European forms than with an}' species occur- 
ing in the lower formation of America. " "In the TuUy limestone 
the latter class are few. " Of this smaller group the following 
fossils have suggested to this author points of comparison with 
species of the Cuboides fauna : 
Or this tulliensis Hall. 
This SchizojjJioria is represented in the middle Devonian 
throughout Europe by the well known 0. striatula and some 
allies. It also occurs in the Cuboides fauna of the Eifel and fre- 
quently in the Intumescens zone. In America the type of struc- 
ture exemplified b}' this species dates as far back as the middle 
Upper Silurian and becomes more or less abundant throughout the 
Devonian, but this species itself, as Mr. Williams has very ac- 
curately said, has a stability of form which is not manifested by 
its successors 0. impressa, 0. lowensis, 0. mac/arlanii ; a feature 
in which it agrees with the earlier Devonian, 0. jJi'ojnnqua, of the 
Corniferous limestone. It would puzzle an expert student to 
point out diflferences of even varietal value between the Cornifer- 
ous and Tully forms, and a palaeontologist better familiar with the 
European than with the American Devonian would certaiul}- refer 
without hesitation both to O. striatula. In the Hamilton fauna of 
New York, 0. TuUiensis is not known to occur, l)ut in the cement 
beds about Milwaukee it appears in association with a strongly 
■emphasized Hamilton fauna. This fauna has been described by 
Mr. R. P. Whitfieldt though the species in question has been 
referred by him to 0. impressa. 
*The Cuboides Zone and its Fauna; A discussion of methods of corre- 
lation. Bull. Geol. Soc. Araer. Vol. i, pp. 481-500, pis. 11-13, 1890. 
fGeology of Wisconsin, vol. iv, p. 324 et sen. 
