February 19, 1897.] 



SCIENCE. 



317 



were used we might get something analogous 

 to entropy, and which, nevertheless, would pos- 

 sess different and possibly interesting proper- 

 ties. Professor Durand has discussed two spe- 

 cial forms which the integrating factor might 

 take for a perfect gas. One of these is where 

 it is a function of the pressure only, and the 

 other in which it is a function of the volume 

 only. 



Books Eeviewed: Frick, Physikalische Tech- 

 nik; Wilkinson, Submarine Cable Laying; 

 Griesbach, Physikalische Propadeutik; Weldon, 

 Physical Measurements. 



SOCIETIES AND ACADEMIES. 



ELEVENTH ANNUAL SESSION OF THE IOWA 

 ACADEMY OF SCIENCES. 



The Iowa Academy of Sciences held its 

 •eleventh annual session in Des Moines Decem- 

 ber 29 and 30, 1896. In the absence of the 

 President, Professor T. P. Hall, Professor W. 

 S. Franklin, First Vice-President, occupied the 

 chair. The following papers were presented : 



'The State Quarry Limestone,' by Professor 

 S. Calvin, describes a series of limestone ledges 

 ■of Devonian age consisting of comminuted parts 

 of braohiopods, crinoids, etc., some of which de- 

 serve to rank as a brachiopod coquina. As now 

 known, limited to a few local deposits in John- 

 son county. It appears to be unconformable ou 

 the Cedar Valley limestone and laid down 

 after an erosion period of considerable length. 

 No such erosion period in the Devonian has 

 hitherto been suspected. The fauna, in some 

 respects unique, contains a remarkable fish bed 

 including the common Devonian type Ptycto- 

 dus, but also the Carboniferous Psephodus. 

 Some of the brachiopods also have Carbonifer- 

 ous affinities. It is probable the beds represent 

 the closing stage of the Devonian. 



' Stages of the Des Moines, or chief Coal-bear- 

 ing Series of Kansas and Southwest Missouri 

 and their equivalents in Iowa,' by C. E. Keyes. 



'Natural Gas in the Drift of Iowa,' by A. 

 G. Leonard, enumerates the different local- 

 ities where natural gas has been noted and re- 

 lation of these to drift sheets. The gas has 

 two possible sources, the underlying coalmeas- 

 lure shales and the vegetable accumulations in 



the drift. The latter are supposed to be the 

 source of the natural gas in Iowa. 



' Results of Recent Geological Work in Madi- 

 son County,' by J. L. Tilton, included discus- 

 sion of the geological formations of the county, 

 distribution of the loess, drift and alluvium, re- 

 lation of present to preglacial drainage, and 

 other features. 



'A Drift Section at Oelwein,' by G. E. Finch ; 

 ' Evidence of a sub-Aftonian Drift in North- 

 eastern Iowa,' byS. W. Beyer, and 'The Bot- 

 any of a Pre-Kansan Peat-Bed,' by T. H 

 MacBride, all dealt with some exposures re- 

 cently studied in the northeastern part of the 

 State which are of special interest as showing 

 very clearly a distinct separation of glacial 

 periods, at least five of which are now known 

 to be well marked by deposits in Iowa. . 



' Additional Observations on the Surface De- 

 posits of Iowa,' by B. Shimek, detailed results 

 of a series of borings and evidence in support 

 of the author's view that the loess deposits in 

 western Iowa are of seolian origin. 



' The Flora of the Sioux Quartzite,' in Iowa, 

 by B. Shimek, included an annotated list of the 

 plants observed by the author on the quartzite 

 exposure in Iowa, with a discussion of its rela- 

 tion to the remaining flora of the State. 



' Notes on the Aquatic Plants of Northern 

 Iowa,' by the same author, included mention 

 particularly of the flowering plants occurriifg in 

 lakes and ponds. 



'Spermaphyta of the Fayette, Iowa, Flora,' 

 by Bruce Fink ; a list including about 700 

 species of plants collected at or near Fayette. 



' Notes on the Flora of Iowa,' by T. Z. Fitz- 

 patrick ; a short list of species new or little 

 known to Iowa flora. 



' The Mechanism for Securing Cross-fertiliza- 

 tion in Salvia lanceolata,^ by G. W. Newton ; a 

 description of the structure of blossom and 

 means of pollination. 



' Notes on some Introduced Plants in Iowa,' 

 by L. H. Pammel ; covering introduction, dis- 

 tribution and economic importance of a number 

 of species. 



' A Study of the Leaf Anatomy of some 

 Species of the Genus Bromus,' by Emma Sir- 

 rine ; giving details of the epidermis, especially 

 the bulliform cells, stereome and mestome. 



