1 64 NATURAL SCIENCE. Sept.. 



H4°F.; members of the perch family, the Apogon thermalis, and the 

 Ambassis thermalis, in water at ii5°F. ; a roach, Leuciscus thermalis, 

 at ii2° F. 



In a hot spring at Pooree (in the province of Bengal), with the 

 thermometer in the water standing at 112° F., carnivorous fishes 

 have been discovered, which would indicate that these must have 

 found and fed on living prey at the same high temperature. Further 

 accounts, moreover, declare that in hot springs in Barbary, in North 

 Africa, living fishes have been taken in water at 172 , while in Manila 

 (one of the Philippine Islands) in water marking 187 F. While 

 travelling in South America, Humboldt and Koupland stated that 

 they saw fishes thrown up alive from a volcano in water at 210 F., but 

 this is, of course, an absurdity which nowadays, it is to be hoped, 

 no one will believe. 



The Dwindling of Limestones. 



In an article on the Dwindling and Disappearance of Limestones 

 (Quart. Journ.Gcol. Soc, vol. xlix., pp. 372-384, pi. xviii., Aug., 1893), 

 Mr. Frank Rutley discusses the question, which he has himself raised, 

 of the possible dissolution of limestones that were formed during the 

 earlier periods of the earth's history. That limestone is dissolved by 

 the action of acidulated waters, and that caverns, "pipes," and other 

 features are formed in the rocks, are facts familiar enough. The author, 

 however, contends that if unlimited time be conceded, there seems no 

 reason why very thick beds of limestone should not wholly disappear; 

 at all events, he thinks that thin ones may easily do so, and thereby 

 certain pages in the life-history of particular localities may be lost for 

 ever. Unfortunately for his argument, the author is unable to bring 

 forward any special evidence in support of it. The Durness Lime- 

 stone of Cambrian age must be of considerable thickness, and yet it 

 has survived many vicissitudes. The Carboniferous Limestone over 

 large areas, though in places riddled with caverns, presents in mass 

 its full thickness ; it passes by alternations of limestone and shale 

 into the beds above and below, while the masses of the insoluble strata 

 above and below are more extensively wasted away. Statistics of 

 the amount of solid matter carried away by rivers and streams prove 

 how large an amount of limestone is dissolved, but, except in the case 

 of thermal springs, the loss of material is not very deep-seated. 



Attention is drawn to the nodular character of some limestones, 

 and the author very properly points out that in some cases a bed of 

 jointed limestone may become weathered into isolated nodules. He 

 proposes to call these nodules residual, as distinct from concretions or 

 segregation-nodules. These residual nodules occur, so far as we 

 know, only where the strata come near the surface ; but they serve 

 to confirm one of the author's conclusions, namely, " That bands of 

 limestone-nodules may, in certain cases, represent what were 



