igS THE JOURNAL OF GEOLOGY. 



ous was the time of greatest transgression of sea over the pres- 

 ent land areas, while the sea in which the Fusulina beds of Europe 

 and America were formed was more circumscribed. 



The Waverly group when traced towards the west gradually 

 takes on the character of deep water formations ; it is persistent 

 through Nevada and California, ^ and is known, from unpublished 

 investigations, to have a similar fauna in these two states. The 

 Waverly probably persisted much longer in the west, than in the 

 east, for in northern Missouri C. R. Keyes ^ has observed that 

 in the midst of an undoubted Burlington fauna a well marked 

 Kinderhook or Waverly fauna reappears. This he explains by 

 Barrande's theory of colonies. It is probably an incursion of 

 the inhabitants of a deeper western sea, where the Waverly had 

 persisted longer, into the shallower eastern waters. The work 

 of the Geological Survey of Arkansas shows that a similar phe- 

 nomenon occurs in that state. The Fayetteville shale, which is 

 probably of Keokuk age, contains a fauna that differs markedly 

 from those of the limestones above and below it. An unpub- 

 lished report by Professor Henry S. Williams shows the occur- 

 rence in the Fayetteville shale of several species that occur in 

 a doubtful upper Devonian or lower Carboniferous black shale 

 in the White Pine district, Nevada. Along with these Devonian 

 or Waverly species occur others that belong much higher, as 

 Proditctus semiretiadatus, and Goniatites conf. sphcericiis. Below the 

 Fayetteville shale is the Boone chert, which at the base contains 

 a decided Burlington fauna, and at the top probably belongs to 

 the Keokuk. This has been observed in so many places that 

 there is no possibility of mistake in the sequence of the strata. 



We have therefore in Arkansas an incursion similar to that in 

 Missouri, except that in Arkansas the incursion came consider- 

 ably later. This is evidence that somewhere in the west the 

 Waverly fauna persisted throughout the Burlington, and at least 

 a part of the Keokuk. This is in accordance with the phenome- 

 non described by Professor C. D. Walcott in Monograph VIII., 



^ Zoe, Vol. III., p. 274; Proc. Calif. Acad. Sci., Oct. 17, 1892. 

 = American Journal of Science, December, 1892, p. 447. 



