Correspondence — Dr. G. Linnarsson. 626 



few, eacli of which was more than sufficient to dam up the drainage 

 in a Highland glen. 



Mr. Miller suggests that " when the mechanics of glaciers is better 

 known," it will appear that the appetite of glaciers for digging will 

 grow with what it feeds on. Possibly this may be so ; but, as the 

 present state of our information on the subject leads us to infer that 

 the laws governing the moYement of rivers of ice are similar to those 

 which determine the flow of streams of water, it seems to me that 

 our knowledge will have to be very much bettered indeed, before 

 such a proposition stands the smallest chance of general acceptance. 



John W. Judd. 



ON THE SILURIAN EOCKS OF SWEDEN. 



Sir, — In the August Number of your Magazine there is a letter 

 from Mr. Hicks directed against me, and though it is of little use to 

 discuss with Mr. Hicks, who, instead of arguments, usually sets forth 

 only assertions, I shall say a few words, in order to point out some 

 mistakes and mis-statements in that letter. 



When Mr. Hicks in the beginning of his letter says, " that Dr. 

 Linnarsson is unable to put forward stronger evidence in opposition 

 to these [Mr. Hicks'] views is clearly a powerful argument in my 

 favour," I must remark that my letter in the June Number (of which 

 here is the question) was not intended to be a critique of Mr. Hicks' 

 views in general, but only to refute his reasonings in the letter in- 

 serted in the May Number- I think that every attentive reader will 

 find that I have sufficiently shown their weakness, and then nothing 

 more can be required. * 



Mr. Hicks now seems to hold it at least possible that the Para- 

 doxides beds of Sweden represent also the lower parts of the Mene- 

 vian beds, but then he adds, to my astonishment, that " there is no 

 evidence of a previous fauna." One might have thought that Mr. 

 Hicks, from what I have written in the April Number of the Geolo- 

 gical Magazine, would have known that there are below the Para- 

 doxides beds two faunas, that Of the Fucoid Sandstone, and that of 

 the Eophyton Sandstone. 



I doubt whether Mr. Hicks knows much more of the stratigra- 

 phical and palseontological characters of the oldest Eussian beds. 

 He himself says, it is true, that, with regard to the Eussian beds, he 

 has " looked to the general order of the deposits, and the general 

 character of the fauna, for a clue." But I dare say that it is my 

 opinions of their age, and not his, that are supported by " the general 

 order of the deposits," and that hardly any one who has the slightest 

 acquaintance with the Swedish and Eussian beds can come to such 

 conclusions as Mr. Hicks in this matter. From the Orthoceras 

 Limestone down to the Dictyonema Schists inclusively, there is quite 

 the same series of beds in the Swedish and the Eussian area, and 

 therefore it cannot be denied that the Dictyonema Schists of both areas 

 are equivalent, ''if the general order of the deposits," to which Mr. 

 Hicks has himself appealed, is to be relied upon. As to " the general 

 character of the fauna," I (and, I think, geologists in general) should 



