410 The American Naturalist [May, 



author calculates that the entire coal supply will be consumed at the 

 end of 112 years from the year reported on, or say by A. D. 2001. 



This is a fair deduction from facts which are known, and from 

 reasonable estimates, the author calls attention to the importance of 

 looking for some " power" or " force " to take the place of that gener- 

 ated by the combustion of coal when that supply shall be exhausted, 

 as it undoubtedly will in little more than three generations. He 

 maintains there is no intelligent ground for the expectation of the dis- 

 covery of any new force, but suggests that physicists study more effec- 

 tive and cheaper methods of obtaining electrical energy. 



The latter part of the paper is devoted to interesting speculations as 

 to the effect of the increased amount of carbon dioxide in the atmos- 

 phere, resulting from the combustion of so much carbon, upon animal 

 and vegetable life. 



Cretacic Marine Currents in France. — At a recent meeting 

 of the Academie des Sciences de Paris, M. Fouque presented a note 

 from M. Munier-Chalmas on the distribution and the direction of the 

 marine currents in France during the upper Cretacic period. He 

 shows the influence of the Alps upon the limitation to the South of 

 that mountain system of certain mollu.-cs :m<l ei-liinnid.s peculiar to 

 southern regions, and gives an interesting picture of the yanishuag 

 from North to South, through the narrow Paris basin, of certain fosfflli 

 peculiar to the northern seas: Micrasters, Belemnites, Rhynchouellas, 



This fact is analogous to what is now going on in the neighborhood 

 of the Straits of Gibraltar. (Revue Scientifique, 9 April, 1892.) 



Professor Marsh on Extinct Horses and Other Mam- 

 malia. 1 — In the American Journal of Science and Arts for April and 

 May, 1892, appear two articles by Professor Marsh on the above sub- 

 jects. As they are rather more than usually envious contributions I 

 literature, they deserve early notice. The first cited is stated in the 

 title to be " On Recent Polydactyle Horses," but it turns out to in- 

 clude a discussion of the extinct ancestors of the horse. This is re- 

 ceded by descriptions of some remarkable examples of horses wi » 

 supernumerary digits, one of which has rudiments of four in t e 

 anterior foot, a number unprecedented in the annals of p 

 The author then gives figures of the feet of the extinct horses, to 



'On Recent Polydactyle Horses, Amer. Journ. Sci. Arts, 1892 V 



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445. J 



