A Geological Reconnoissance. 177 



ductive cells of ferns or flowering plants but is frequently met 

 with in the stalk of the sporangium {^Bjtrychiiim) ; and karyo- 

 kinetic nuclei in all stages of division, although not in great 

 abundance in any one field, may be found in the meristemic 

 tissue in the tips of the young shoots of conifers. The leaf 

 buds should be collected in the spring after growth has begun. 

 Sections in the region of the scale-like leaves will present 

 nuclei which ma}' be studied even under the one-fifth objective. 



Botanical Laboratory^ S. U. /., lilay, iSg2. 



A GEOLOGICAL RECOXNOISSANCE BUCHANAN COUNTY, IOWA. 



By S. CALVIX, 



In October, 1S91, the writer in compan}' with Mr. G. L. 

 Houser made a careful examination into the geological struct- 

 ure of portions of Buchanan county, Iov»'a. A part of the 

 same region had been rather hurriedly examined a few months 

 earlier, and the results of that prehminary work had been 

 published, September, 1891, in the American Geologist, Vol. 

 VIII, p. 142. K few errors were made, as usual, in the hasty 

 preliminary observations, the onl}' one of any consequence 

 being that which is corrected in the Gcoiogist^Yol. IX, p. 345. 



The object in view in re-examining the region was to 

 determine more carefully than had before been done the 

 stratigraohical relations of the various beds of the remon: to 

 ascertain the relative position and vertical range of the several 

 fossil species, the species in this locaHty being conspicuously 

 associated in groups and confined to horizons of limited verti- 

 cal extent; and lastly to find in place if possible the beds con- 

 taining Rensclaria johanni, or Ncjuherrya johannis as it is now 

 called, and so fix its horizon, a point which had been left 

 undetermined in the previous examination. 



