124 JULES MARCOU ON THE TACONIC OF GEORGIA 



The figure of Barrcmdia {Olenus) Thompsoni, p. 116, is much Ixttor than in the first 

 paper of 1859, giving on the c-audal sliiehl '' a slender pointed spine strengthened ])y a 

 sharp elevated ridge, extending to the extremity;" but failing to give the remailvable cau- 

 dal spine, more than two inches long and spade-like, Avhich I have found on a specimen 

 at the Parker's quarry in 18G1, and which has been figured since by Mr. AVhitfield in 

 Bulletin Amer. Museum Nat. Hist., New York, Yol. i, I^o. 5, Plate xv, fig. 1, 1881. 



Another and important difference between Mr. Hall's paper on the three trilobites of 

 Georgia of 1859 and the one of 1861 (occasioned by the publication of Barrande and 

 Marcou's memoir in December, 1860), besides the creation of the so-called genera Bar- 

 randia and Bathynotus, is the suppression at the end, of the celebi-ated authoritative 

 note on the age of the Hudson River group, and Logan's ability as a stratigraphist, which 

 is replaced by the following note: "The geological horizon of the shales in which these 

 trilobites occur having been made a matter of discussion among geologists, I shall refer 

 those interested in the subject to the forthcoming report upon the geology of the state 

 of Yermont by Prof. E. Hitchcock" (see p. 119, "Thirteenth Ann. Kep."). The nomen- 

 clature and classification contained in that report having been given previously, with the 

 quotation of the sentence, " The stratigraphical view of the Georgia slate, which has 

 been so ably defended by Professor Hall, etc.," it is sufficient to say that Professor 

 Hitchcock was no more aware of the true geological horizon of those trilobites than 

 Professor Hall, and that both had wandered astray in dealing with the paleontological 

 and geological elements of the Georgia formation. 



1861 (Sept.). Mr. Marcou in a letter to Elie de Beaumont, written during his visit at 

 the honse of jN^. E. Parker, Georgia, gives the first description of the Schistes armaces d 

 trilobites de Georgia, and places them as a subdivision of the Schistes de St. Albans in 

 the Upper Taconic. For the first time also, he signalizes the existence of great lentic- 

 idar masses of very hard limestone, badly stratified and inclosed in the slates, round the 

 city of St. Albans. (See Coviptes Rendas, Academie des Sciences, tome liii, No. 19, 

 4 Novembre, 18()1, pp. 803 to 808, Paris.) 



1861 (Nov.). -^t the 6th of November meeting of the Boston Society of Natural His- 

 tory, Mr. Marcou desci'ibed, with details and sections, the Georgia slates as the middle 

 grou]) of the Taconic. He gave also a history of the discovery of the fossils in the 

 quarry of N. E. Parker. This is the first detailed description of what Mr. Walcott calls 

 Georgia formation. The sections drawn on the blackboard were not published until 

 1880, in Mr. Marcou's paper printed in the Bulletin Sac. geol. France, 3® serie, tome ix, 

 p. 18: " Sur les colonies dans les roches Taconiques des boi'ds du lac Chamijlain," p. 24 

 and Plate ir, fig. 1. 



The communication to the Boston Society is entitled: " The Taconic and Lower Silur- 

 ian rocks of Yermont and Canada," by Jules Marcou (Proceed. Boston Soc. Nat. Hist., 

 Yol. VIII, 1861 to 1862, p. 239) ; and it is at pp. 244, 245 and 216, that the Georgia slates 

 arc descriljcd as a special group. 



1862 (Mar.). In the "Report on the Geology of Yermont," by Edward Hitchcock and 

 Charles H. Hitchcock, in two volumes, 4", antedated 1861, but not published until the 

 end of March, 18(52, at p. 357 there is a Georgia groiqy. No description of Parker's 

 quarr}^ or any other part of Georgia township is given. 



The second edition of Professor Hall's paper on the thi'ce trilobites of Georgia, taken 



