NO. 1S50. KNOBSTOXE CRIXOID FAUNA— SPRINCIER. 183 



3. Tliat tliis fauna includes a number of reputed Keokuk species 

 occurring at Wliites Creek Springs, Tennessee, where true Keokuk 

 forms are also kno"\\Ti to occur; among these the rare '^ IcJithyocrinus^' 

 tiarseformis of Troost. 



As the Whites Creek region was known to present a section from 

 the Niagara to the Warsaw, and to be one of tremendous erosion, 

 it now seemed probable that the equivalent of the Button-mould 

 Knob beds would be found there, although not heretofore recognized, 

 with an intermmgling of fossils from the erosion of these and the 

 overlying Keokuk beds, wliich would account for the confusion of 

 faunas already mentioned. I therefore thought it advisable to have 

 that region carefully searched anew, under the guidance of an expe- 

 rienced geologist. I was so fortunate as to enlist the interest of Dr. 

 R. S. Bassler, of the U. S. National Museum, in the c|uestion, and he 

 readily consented to undertake the examination, which he made in 

 company with Mr. Braun, in June, 1910, after first carefully studying 

 the beds at Button-mould Knob and vicinity. My thanks are due to 

 Dr. Richard Rathbun, assistant secretary of the Smithsonian Insti- 

 tution, for kindly granting Doctor Bassler leave of absence from office 

 duties for that purpose. 



Doctor Bassler's observations, more fully set forth in his accom- 

 panying paper, clearly demonstrated that the Button-mould Knob 

 beds are present at Wliites Creek, and fully confirmed the suspicion 

 of the interminghng of their fossils with those of the Keokuk lime- 

 stones above. His researches have cleared up the complex stratig- 

 raphy of that region, and placed the correlation of the Ejiobstone 

 beds upon a sound basis, as shown in his account, where the geological 

 details are given m full. A series of authentic collections, made at 

 the same time by j\Ir. Braun, makes possible a close comj^arison of the 

 Whites Creek fauna with that of the Knobs. In addition to this, I 

 have had the advantage of examining the collection of the Vander- 

 bilt Univei-sity m Nashville, which was generously placed at my dis- 

 posal by Prof. L. C. Glenn, of the department of geology of that 

 mstitution. It mcludes the original collection of Safford, with others 

 since made by Professor Glemi, and is a useful addition to the other 

 material when interpreted in the fight of our present knowledge of the 

 Whites Creek beds. 



I may mention also that durmg Mr. Braun's work of 1909 he made 

 a general coUection of other fossils at the Knobs, which I placed in the 

 hands of Doctor WeUer, who mforms me that he finds them of a 

 decidedly pre-Keokuk type. And in this connection I would also 

 caU attention to WeUer's paper on the fauna of the Fern Glen forma- 

 tion,^ from shaly layers immediately underlying fimestones referable 



1 Bull. Geol. Soc. America, vol. 20, pp. 26.5-332. 



