MICROSCOPIC STRUCTURE OF SILICIOUS OOLITE. 627 



The following three papers ^Yere read l^}^ title, in the absence of the 

 authors. 



INTERGLACIAL SERIES OF GERMANY 

 BY DR ALFRED .lEN^TZSCK, KONIGSBURG, PRUSSIA 



This paper is published in full in The American Geologist, volume 

 xiii, INIarch, 1894, page 221. 



THE 31 AD ISO X TYPE OF DRUMLINS 



BY WARREX UPIIA>[ 



DIVERSITY OF THE GLACIAL DRIFT ALONG ITS BOUNDARY 



BY WARREN UPHAM 



Abstracts of the papers by Mr Upham are published in The American 

 Geologist, volume xiii, March, 1894, pages 222-223. 



The following paper was read : 



MICR OSCOPIC S TR UCTURE O F SI LI CIO US O ULITE 

 BY E. O. HOVEY 



Contents 



Page 



Silicious Oolite from Pennsylvania G'27 



Siiioious Oolite from New Jersey C29 



Silicious Oolite from Pexnsylvama.* 



In the American Journal of Science f for September, 1890, -Messrs E. H. Barbour 

 and J. Torrey describe a sihcious ooUte from near State College, Center count}-, 

 Pennsylvania, giving ciiemical analyses and figures of microsections of the rock. 

 The microscopic characters described by Dr Barbour are practically summed up in 

 the following quotation from his article : 



" A fractured surface of the silicious variety exposes the component spherules in section, show- 

 ing their concretionary structure, their concentric coats of alternately lighter and darker color, 

 deposited around real or imaginary centers. In many, organic remains are the nuclei ; in others, 

 crystals or fragments of inorganic matter." 



The author quoted does not seem to have used polarized light in studying his 

 sections, and as the use of this medium reveals the structure of the rock very 

 clearly and ])rings out some points not mentioned in the article to which the reader 

 is referred, it seems worth while to add some observations to those already pub- 

 lished. 



*My thanks are due to Mr L. V. Pirsson, of the Sheffield Scientific School, not only for the 

 specimen and section on which this investigation was made, but also for valuable suggestions 

 during its progress. 



t Vol. Ill, X I, pp. 240-249. 



