496 



Scientific Intelligence. 



7 square centimeters of base and a column of 10 centimeters in 

 height the sensitiveness was such that the difference of potential 

 corresponding to a striking distance of 1 millimeter between balls 

 six centimeters in diameter gave a deviation of 25 centimeters 

 upon the scale. The authors describe certain modifications of 

 the apparatus. They are able to obtain instruments which are 

 sensitive to 5 volts, and can serve to measure 1000 to 1500 volts. 

 By altering the thickness of the plates of quartz, instruments of 

 almost any suitable range can be constructed. The authors re- 

 ply to a remark, that an optical manometer depending upon inter- 

 ference fringes might be made more sensitive than the manometre 

 piezo-electrique, which they describe, by stating that admitting 

 that one can measure to y^- of a fringe in the compensator of 

 Babinet one could obtain a manometer sensitive to a pressure of 

 three kilograms ; whereas their electrical manometer is six 

 hundred times more sensitive and indicates a pressure of five 

 grams. — Journal de Physique, April, 1889, pp. 149-168. j. t. 



II. Geology and Natural History. 



1. Triassic Plants of Eastern North America. — Dr. Stur has 

 reviewed (Verb. G. Reichsanst. July 31, 1888) the plants of the 

 Triassic beds of Virginia described by Prof. Fontaine, with speci- 

 mens before him, received, as he states, from Prof. Fontaine. He 

 publishes the following list of species identified by him with 

 species from the Lettenkohle, the lower division of the Upper 

 Trias of Germany. 



Clover Hill, near Richmond, Va. 

 Equisetum Rogersi Schirnper. 

 Schizoneura Virginiensis Font. 

 Macrotozniopteris magnifolia Rogers. 



" crassinervis Font. 



Acrostichides Linnowefolius Bunb. 



" rhombi/olius Font. 



" densifolius Font. 



" microphyllus Font. 



Mertensides bullatus Bunb. 

 " distans Font. 



Asterocarpus Virginiensis Font. 



" platyrrachys Font. 



" penticarpus Font. 



Lonchopteris Virginiensis Font. 

 Clathropteris platyphylla Font. 

 Pseudo-danceopteris reticulata Font. 

 Ctenophyllum Braunianum Font. 



" grandifoliurn Font. 



Podozamites tenuistriatus Font. 

 Sphenozamites Rogersianus Font. 



Schists of Lunz. 

 Equisetum arenaceum Jaeger. 

 Calamites Meriani Brgt. 

 Tamiopteris latior and T. simplex Stur. 

 ? 



? 



Speirocarpus Lunzensis Stur. 



" Rutimeyeri Heer. 



" microphyllus Stur. 



Oligocarpia robustior Stur. 



" Lunzensis Stur. 



Asterotheca Meriani Brgt. 



Sperocarpus Haberfelneri Stur. 

 Clathropteris reticulata Kurr. 

 Heeria Lunzensis Stur. 

 Pterophyllum Riegeri Stur. 



" Haueri Stur. 



? 



" Bronnii Schenk. 



Relations are also shown between other American and German 

 species, and the conclusion reached that the American beds are 

 equivalents of the Lettenkohle. 



In the same paper, Stur presents facts from the European Per- 

 mian flora favoring the view that the Glossopteris flora of India, 

 Afghanistan, Australia, and South Africa, is Permian. 



