254 TRANSACTIONS OF THE [mAR. 15, 



miles. They and the sandstone appear, in man}' places, to be 

 mutuall}' replaceable. The thickness of the Batesvilie sandstone 

 is very changeable, var^'ing from twenty or thirty feet to almost 

 two hundred feet." 



In Professor Symond's * report a sandstone formation in 

 Washington county, Arkansas, is referred to the Batesvilie sand- 

 stone on wholl}' stratigraphic and structural evidence. In Dr. 

 Branner's introduction to this report, on page 13, in a table on 

 " The Formations of Washington County," the Batesvilie sand- 

 stone is placed, on the authority of Professor H. S. Williams, as 

 the uppermost member of the Osage group. This was the first 

 attempt made to correlate the formation, and it is only just to 

 Professor Williams to state that this determination of its posi- 

 tion was made upon a limited examination of the fossils. 



1893. — During this year appeared the report of Mr. T. C. Hop- 

 kins | on the marbles of Arkansas. On page 10 of this report is a 

 table showing the " General classification of the rocks of north 

 Arkansas." So far as the Carboniferous beds are concerned, 

 this table is in substance a reproduction ot Dr. Branner's table 

 in the Washington county report, the Batesvilie sandstone being 

 assigned to a position at the top of the Osage group. 



1894. — In the report on the geology of IBenton county, by F. 

 W. Symonds and T. C. Hopkins, | the same formation is de- 

 scribed, which was referred to the Batesvilie sandstone in the 

 Washington county report. The formation is treated structur- 

 ally, stratigraphicall}' and economically onl}-, and nothing new is 

 shown as to its exact position in the Mississippian series. 



1895. — During this j^ear, in a paper entitled " On the recur- 

 rence of Devonian fossils in strata of Carboniferous age," Pro- 

 fessor H. S. Williams § referred to the Batesvilie sandstone as 

 belonging to the " Chester-St. Louis horizon." 



Part II. Description of Species. 

 MOLLUSCOIDEA. 



POLYZOA. 



There are in the collection several species of Poh'zoa repre- 

 senting several genera. In the condition of preservation, how- 

 ever, as impressions in the sandstone, the details of structure 

 are too poorly shown to allow of accurate identification. 



*The Geology of Washinton count}', bv F. W. Svmonds, Ph. D., Assistant Geologist- 

 Ann. Rep. Geol. Surv. Ark. for 1888, Vol. iV., Little Rock, 1891. Pp. 49-53. 



t Marbles and other limestones, by T. C. Hopkins. Ann. Rep. Geol. Surv. Ark. for 

 1890, Vol. IV., Little Rock, 1893. 



JThe Geology of Benton county, by F. W. Svmonds and T. ('. Hepkins. Ann. Rep. 

 Geol. Surv. Ark for 1891, Vol. II. 



g Am. Jour. Sci. (3), Vol. LIX., pp. 91-101. 



