[Annals N. Y. Acad. Sci., Vol. XX11, pp. 1-8, PI. I. 3 April, 1912.] 



ON SOME INVEETEBEATE FOSSILS FEOM THE LYKINS 

 FOEMATION OP EASTEBN COLOEADO x 



By George H. Girty 



(Read by title before the Academy, 5 February, 1912) 



The fossils which form the subject of the following account were col- 

 lected by Mr. Eoy M. Butters and kindly placed by him in my hands for 

 study. They were obtained in the Lykins formation of Colorado and 

 represent a horizon in the Paleozoic higher than any at which fossils have 

 heretofore been found along the eastern flank of the Front Eange. 



A detailed account of the stratigraphic relations and correlation of the 

 Lykins formation has been prepared and will shortly be published by Mr. 

 Butters. To a manuscript of this report, which I have been permitted to 

 read, I largely owe the following data which seemed essential to the 

 understanding of this limited but interesting fauna. 



The "Eed Beds" of the Front Eange in Colorado have been variously 

 classified and named. Their nomenclature and synonymy is, therefore, 

 rather complicated, but as a general statement, it may be said that the 

 Wyoming formation of Emmons has been divided into three formations, 

 of which the Lykins is the highest. Below the Lykins, there occurs a 

 series of strata (the lower Wyoming) which are now known as the Foun- 

 tain and Lyons formations, while above the Lykins is the Morrison for- 

 mation. The Lykins, therefore, belongs in the upper "Eed Beds" of this 

 area. The Fountain has furnished more or less conclusive paleontologic 

 evidence of Pennsylvanian, or at least of upper Carboniferous, age, while 

 the Morrison has long been known to be Mesozoic. The Lykins forma- 

 tion, from which fossils have not hitherto been known, has usually been 

 assigned to the Triassic, but the evidence herewith presented seems to 

 show conclusively that the formation, or at all events that portion of it 

 from which the fossils were obtained, is Paleozoic. Provisionally, I am 

 assigning the Lykins fauna to the Permian, though more on account of 

 its position at the top of the Paleozoic section than on account of any 

 very close resemblance either to the Permian of Eussia, the more or less 

 doubtful Permian of our Western States or the Permian as distinguished 

 from the Pennsylvanian of the Mississippi Valley. The only fauna in 



1 Published by permission of the Director of the U. S. Geological Survey. 



