NO. 185©. KfiOBSTOyE CRINOID FAUNA— f^PRINGER. 185 



and if below the upper level of the latter, may be from both inter- 

 mingled. This was the condition in a plowed field where Wachsmiith, 

 over 20 years, ago, made one of the best collections ever obtained 

 at ^Vliites Creek, in which the fossils, although evidently mostlv from 

 the gray limestone, as we now know, were nearly all of the reddish 

 or yellowish color of the soil. In fact, we not infrequently find a 

 specimen wliich is partly reddish and partly bluish, from havmg been 

 buried in partial contact with a clay derived from one or the other of 

 the beds. 



Furthermore, in such limestones as these gray beds we may ex- 

 pect small bands or pockets colored with ferric oxide, from which 

 the fossils come out reddish or yellowish. This is quite frequent in 

 the limestones and cherts at Burlington. I would also expect to 

 find the bluish color from the lower beds running up to the Keokuk 

 layers. 



Hence we can not depend upon color as a guide to the origin of 

 the specimens, and it should be disregarded altogether in their con- 

 sideration. 



Alio pro sallocrinus conicus, for mstance, is an unquestioned Keokuk 

 species, and we find it both red and blue ; so with Lohocrinus nash- 

 villae, and Agaricocrinus americanus. On the other hand, species 

 knoAVTi to occur in the Knobstone layers of Button-mould Knob are 

 found here in both colors — -as, for mstance, Meticlithyocrinus tiarae- 

 formis, Catillocrinus tennesseensis, etc. In general, it may be said 

 that the fossils from the lower lunestone are usually more solid flint, 

 and less often geodized, while those of the Keokuk beds are more 

 imperfectly silicified, and frequently geodized. Neither is this a 

 reliable criterion, as these differences are sometimes found elsewhere 

 in one and the same bed. 



The crinoids of this locality are more frequently found intact 

 than at the Knobs, and we w^ere fortunate in securing a fair series of 

 them from each bed m place; these furnish a firm basis of compari- 

 son to begin with. They include the following species: 



A. Undoubted Keokuk, from top of hills: 

 Agaricocrinus americanus. 

 Agaricocrinus nodulosus. 

 Lohocrinus nasTivillae. 

 Alloprosallocrinus conicus. 

 Eretmocrinus ramulosus. 

 Eretmocrinus praegravis. 

 Dorycnnus gouldi. 



B. Below the Keokuk, in grey limestone: 



Eretmocrinus, large arm fragments and parts of calyx — probably 

 E. yandelli. 



