FIFTH ANNUAL MEETING. 39 



The following is the list, which we believe includes nearly all the 

 mollusks thus far found in the red randstone within the bounds of 

 Kansas : 



Crassatellina oblonga. 

 Area (?) parallela. 

 Yoldia microdonta. 

 Cardium Kansensis. 

 Cardium (Protocardia) Salinense. 

 Cyrena (Corbicula?) nucalis. 

 Cyrena(Corbicula?)subtrigonalis. 

 Tellina subscitula. 

 Tellina (?) mactroides. 

 Leptosolen Conradi. 

 Turritella Kansensis. 

 Turbo Mudgeanus. 

 These shells are in the same strata and in the vicinity of several 

 deposits of the dicotyledonous leaves, and with the plants identify 

 this portion of the sandstone as belonging to the Dakota group of 

 the Cretaceous, as described by Meek and Hayden in their first 

 report. 



The sandstone varies in a great degree in various localities, and 

 even in the same quarry. In color it varies from white to nearly 

 black, but usually of a dark brown. Much of it makes an excellent 

 building material, being durable and easily wrought. 



Within the past four years the leaves have been found lower 

 down, or nearer the Permian than they were previously known to 

 exist. Those at the bottom of the well in Clay county must have 

 been less than two hundred feet from the Permian. 



The line of demarkation between the different geological forma- 

 tions of Kansas are very obscure. A physical unconformability I 

 have never seen, and the division, as shown by a difference of fossils, 

 the best criterion, is also very indistinct. We must consider, also,, 

 that the sandstones called Triassic and the Cretaceous in Kansas 

 are so similar in color, hardness, fineness, and chemical elements, 

 that were a hundred tons of each thrown into the door yard of Dana,, 

 the great geologist and mineralogist, he could not, from any of the 

 characteristics (aside from fossils) tell to which of the two forma- 

 tions either pile belonged. 



