26 IOWA ACADEMY OF SCIE^XES. 



than the phjlogenetic history of the group. The correct determinations of the- 

 phylogeny of animals from paleontological evidence is attended with many difficul- 

 ties, for, as repeatedly shown by Darwin and others, new variations tend to be 

 transfered backward in the ontogenetic history of a. species, and may dispose older 

 characters. 'Ibis taken in connection with the fact that variant changes may 

 occur in one part of an organism without materially affecting other parts, calls for 

 extreme conservatism m passing judgment on phyogenetic problems from evidence- 

 afforded by fossils. 



AGE OF CERTAIN SANDSTONES NEAR IOWA CITY. 



BY CHARLES R. KEYES. 



The sandstones under consideration lie in old gorges in Devonian limestone a 

 short distance north of Iowa City. On account of the presence of plant remains, 

 which, however, were too fragmentary for identification. Hall regarded the 

 arenaceous deposits as belonging to the upper coal measures. Others visiting the 

 places, since the announcement of the discovery in 1858, have adopted the same 

 view as to the age of the rock, without attempting to question the correctness of 

 the assumption, or to obtain further evidence. 



Lately some molluFcan remains have been found in the sandstones. Comparisons 

 show that they are very closely related to Kinderhook species occurring abund- 

 antly in the yellow sandstone at Burlington. IVlore perfect specimens however 

 are necessary before final judgment can be passed. Careful research will, no 

 doubt, reveal soon large numbers of good fossils in the beds in question. 



The Kinderhook is well exposed i-outh of Iowa City at Burlington, and north- 

 westward at Le Grand, in Marshall county. It is probable that exposures are 

 accessible at numerous intermediate places. The Burlington limestone— the 

 stratum superimposed immediately upon the Kinderhook in Iowa, is said to be well 

 exposed northward from the city of Burlington to within 9 miles of Iowa City. 

 Hitherto the shore deposits of the Kinderhook have not been recognized in Iowa 

 except near Burlington. The Iowa City locality fills up the gap. However^ 

 some additional information is required before the question can be regarded as. 

 deflnitely settled. And the present note is merely suggestive. 



NOTES ON THE BEDROCK SANDSTONE. 



BY CHARLES R. KEYES. 



The sandstone of Redrcck, in Marion county, Iowa, has long attracted popular 

 attention. The bright vermillion cliffs rise to a height of one hundred to one hun- 

 dred and fifty feet above the water surface of the Des Moines river. The red col- 

 oration of the rock, however, is ocal. The formation has a known geographic 



