92 Correspondence — Mr. David Forbes, 



the lowest rocks of tlie Silurian ; in the strata of the Old Eed Sand- 

 stone the schists are marked with the little microscopic spots where 

 they have been. In many limestones they are well preserved; in 

 the Coal-series they are so abundant that they make up massive 

 layers, and so through all the groups, as plentifully in the marine as 

 in the fresh-water beds. Existing as they did in such vast numbers 

 in the waters and muds of the ancient seas and rivers, it necessarily 

 follows that the accumulated shells of the dead specimens should far 

 outnumber the living ; and when we examine our ponds, etc., at the 

 present day, and find them teeming with this form of animal life, we 

 may understand how largely these minute Crustacea have contributed 

 to form the carbonate of lime in the various rocks above mentioned. 

 The speaker explained how new forms had been discovered in the 

 mud of foreign countries, and requested his hearers to induce any of 

 their friends who might be going abroad to bring or send home pill- 

 boxes filled with the dried mud of any of the rivers or lakes they 

 might pass in their travels. By keeping these carefully separated, 

 and putting them in distilled water on their arrival in this country, 

 he said that many new and interesting species might be developed. 

 Land and Water ^ January 18, 1868. 



coI^I^:Es:poIs^x)EI5^CE. 



DE. T. STEEEY HUNT'S GEOLOGICAL CHEMISTEY. 



Sir, — In the last number of the " Chemical News" ' (Jan. 17), Dr 

 Sterry Hunt has inserted a reply to some remarks of mine contained 

 in No. 409 of that Journal, but which, in reality, is in great part a 

 criticism on the contents of my communication to the Geological 

 Magazine for October last, the substance of which Dr. Hunt accuses 

 me of having, " for some unknown reason, witheld from the readers 

 of the ' Chemical News.' " The absurdity of this accusation is self- 

 evident, as in the '' Chemical News " the reader is distinctly given to 

 understand that the communication was but a supplement to the 

 previous one in the Geological Magazine of October 1st ; and, as you 

 are aware, in the Geological Magazine of that date, special attention 

 is directed to this forthcoming supplement. I would, therefore, ask 

 the favour of your inserting in your forthcoming number the enclosed 

 communication, which, by also appearing in the next number of the 

 "Chemical News," will, I hope, satisfy Dr. Hunt that it is not my 

 wish to withold any of the points of this controversy either from the 

 readers of the *' Chemical News " or of the Geological Magazine. 



20^A Decetnber, 1868. DaVID FoRBES. 



^ If the reader will compare the article by Dr. T. Sterry Hunt, in the Chemical 

 News, here referred to, with that contained in our present Number, p. 49, he will 

 perceive, that, to a great extent, they are the same ; this letter is therefore capable 

 of being treated as a reply, in part, to both of Dr. Sterry Hunt's communications ; 

 but there are several points discussed by Dr. Hunt in this Magazine which are not 

 entered upon in the Chemical News. To these Mr. Forbes will no doubt reply after 

 he has seen and compared the two articles.— Ed. 



