BIOGi?APHICAL SKETCH OF ISAAC LEA, LL. D. XLIX 



that tliere is really no difference of opinion between ns as to their being in his "Red 

 Shale" (Formation No. XI), as I expressly stated in uiy description, the spot being 

 laid down to the foot, taking his own measurements as to the thickness of the strata 

 there. The ditFerence is not as to a geological error on my part, but whether his 

 '•'Red Shale formation" (Formation No. XI) be part of the Old Eed Sandstone or 

 not. In this I followed the opinion of Mr. Taylor, Mr. Hall, Mr. Vauusem, M. de 

 Verneuil, &c. 



The expression on the part of Mr. Rogers iu regard to the position of these "foot- 

 marks " I always thought was disingenuous in reference to mc, and certainly unjust ; 

 because it was intended to detract from any merit that the discovery might give me, 

 when there could really be no doubt as to the position of the "foot-marks" being 

 <«'o formations below the Coal formation. No. XIII, and in his Formation No. XI, "Red 

 Shale formation." 



I therefore have not modified my views, because we have had no additional geo- 

 logical evidence calculated to change the opinions of the distinguished geologists 

 above mentioned. They may all prove wrong, but we must have the facts to 

 show it. 



I am not at all surprised at what you say of Agassiz's opinion regarding the "foot- 

 marks." His second attempt at this organism is almost as bad as the first. There is 

 a wide difference between a fish and a toad. He has oscillated to an extreme point 

 now, and will doubtless have to come down to the Saurian point ; nothing else will 

 do, I am sure, for my " foot-marks." * I should like much to know what he has said 

 in his lectures regarding them. Pray, have they been printed or reported ? 



If you intend to refer to reptilian life in the Devonian of England, Telerpeton elgi- 

 nense Mautell, you will find a note in my new folio edition of the Memoirs, ]>. 13, by 

 which you will see there is some doubt as to that formation. I will send you a copy 

 of this edition with great pleasure as soon as I get some from the binder. In the> 

 mean time you may see it in the Cambridge Library or at Dr. Warren's. Had I had 

 the pleasure of your acquaintance before I certainly should have sent you a copy in 

 the box with those for other friends. I suppose you have seen my memoir on the 

 fossil saurian of the " New Eed," j)ublished in the second volume of the Journal of 

 the A. N. S. I will do myself the pleasure to send you a copy. 



I shall probably go to Pottsville in a week or two, having business there with ten- 

 ants working coal-lands. I have been anxious to examine the localities east and 

 west of that where I first found my specimen. I need not say that it would give me 

 great pleasure to show you this specimen or anything else I have, and it will at all 

 times gratify mc to be able to promote the views of one who has done so much for 

 science as yourself. 



I am, very truly and sincerely, yours, 



ISAAC LEA. 



Prof. Jeffkies Wyman. 



Cambridge, Mass., June 7, 1855. 



■* * * Your kind letter of May 21 was duly received, and I thank you for tho 

 information which it contained. It so happened that on the day following the date 

 of my letter I had an opportunity of seeing your admirable monograph at the rooms 

 of the Boston Society of Natural History. 



The specimens which are now iu my possession contain the tracks of a much smaller 

 animal than those figured in your memoir. In fact I have two species, the natural 

 sizes of which may be seen in the figures below, which are somewhat exaggeratt'd in 

 point of distinctness as regards the larger species. I think Agassiz will not again 



* Is it not singular that he should, over the same specimens, give such different 

 opinions, so far removed from each other? He saw Professor Rogers's specimens at 

 Albany and pronounced them fish ; ho now sees the same with you and pronounces 

 them toads. 



1748— Bull. 23 IV 



