Professor T. R. Jones — Chalk Foramiuifera. 225 



Now contrast the foregoing inadequacy of denudation as acting 

 to set free "fossil sea-water" with denudation as dissolving the 

 alkali-silicates, the latter action being very interestingly brought 

 out by Mr. Fislier himself in his estimate of the rate of denudation 

 required to maintain the river supply of alkalies. I venture to 

 claim that Mr. Fisher has strongly supported ray view in showing 

 that — uVo- of a foot of granite removed per annum over the land 

 area would suffice to supply the sodium of the rivers. In this 

 connection I again urge that detrital rocks passing more readily 

 into soils and exposing finer material to sui'face actions probably 

 contribute quite as effectively as eruptive rocks to the supply of 

 alkalies. 



Finally, in reference to ]\Ir. Clarke's estimate of the crust 

 constituents, it is worth noting that this estimate is not derived 

 in such a manner as to include extravasated substances. As 

 I gather, it is founded on typical rock analyses. Now chlorine, as 

 it happens, entering only with difficulty into the constitution of 

 silicates, occurs chiefly as an extravasated substance. Hence we find 

 it abundant in mineral springs of volcanic regions and in association 

 with ores. Springs arising in connection with lodes ai'e often 

 heavily charged with chlorides. The sources of supply are in these 

 cases probably deep-seated, and would not enter into estimates of 

 crust constituents based on rock analyses. It will be at once 

 apparent, too, that saline waters, where entering occasionally into 

 deep-seated bedded rocks, may well be derived from such sources ; 

 or, again, from inland waters of former times which had never 

 communicated with the ocean. The very various composition of 

 such waters from deep wells supports their non-oceanic oi*igin. 

 For the greater part these sources of chlorine are to be included 

 on the side of the crust constituents and (for a large part) so far 

 as they include sodium in combination, go towards explaining the 

 discrepancy, such as it is, in the equation between the sodium 

 missing from the sediments and the sodium of the ocean. 



We have no reason to suppose the contributions from these 

 sources to the rivers to have varied in one or the other direction 

 during the past. 



V. — Catalogue of the known Foraminifeka fkom the Chalk 



AND ChaLKMARL^ OF THE SoUTH AND SoUTH-EaSTERN COUNTIES 



OF England. 



By Prot. T. Rupert Jones, F.R.S., F.G.S. 



The sources of information are given below. 

 D. From T. Rupert Jones's Catalogue of the Foraminifera from 

 the Chalk and Chalkmarl in the Second Edition of Dixon's 

 " Geology and Fossils of Sussex," 1878, pp. 284 and 285. 



' It is not here practicable to divide the Forarainil'cra behmj^iug screrally to tlie 

 two formations ; hut some indication of the distribution is sliown by the list at 

 pp. 284 and 285 of Dixon's " Sussex," 2nd edition, 1878. Of the range of these 

 Foraminifera in earlier strata of tlie Cretaceous series, some particulars may bs 

 gathered from the list published in Topley's " Geology of the Weald " (Mem. Geol. 

 Surv., 1875, pp. 423 and 424), as far as known at that time. 



DECADE IT. VOL. VII.— XO. V. 15 



