OF ARTS AND SCIENCES. 201 



" Je vous prie d'exprimer plus particulicrement a Madame Marcou 

 mes sinceres reaierciments pour ses traductions* aussi elegantes que 

 fideles. Agreez mou cher coufrere Texpressiou de tous mes senti- 

 ments tres distingues. 



" J. Barrande." 



After this successful beginning, the Taconic question demanded 

 minute and careful study in the field in order to be fully decided. Its 

 adversaries had conceded something ; it became necessary to pursue 

 the research, and to clear up the stratigraphy of the borders of Lake 

 Champlain and the environs of Quebec. Urged by Colonel Jevvett, 

 Barrande, Agassiz, and Billings to undertake this work, as an extract 

 from a letter of Billings to Colonel Jewett will show, I resolved to 

 devote myself to tliis difficult and ungrateful task ; and in September, 

 18G1, I started for Vermont. 



"Montreal, July 30, 18G1. 

 "Mr DEAR Colonel Jewett: — 



". . . . I send you by express to-day a Trilobite from the Red 

 Sandrock of Vermont. It is a Conocephalites allied to C mhmtus of 

 the Potsdam, but still a distinct species. This Trilobite proves very 

 clearly that the Red Sandrock of Vermont is either the Potsdam or 

 the base of the Calciferous. The genus Conocephalites is a true Pri- 

 mordial type. No species of this genus is found above the base of 

 the Lower Silurian. This puts an end to the idea that the Red 

 Sandrock is the Medina sandstone. Besides, I have other evidence. 

 I lately spent tlu-ee weeks at Phillipsburgh on Missisquoi Bay exam- 

 ining into the age of this formation. At Phillipsburgh the Calcifer- 

 ous f is laid bare over an area of eight miles in length by about 

 three in width. Along the shore of the bay- it forms a precipice, from 

 fifty to one hundred feet high, for three miles. The base of the 

 cliff is composed of slate as at Sharp Shins. The Calciferous rests 

 upon the slate unconformably. [This is a mistake, for the limestone 

 is enclosed in the slates. — J. M.] I found here (in the Calciferous) 

 about forty species, most of them new. Of the described species I 



* Mrs. Marcou translated into English tlie three letters of Barrande of the 

 29th May, 16th July, and 14th August, 1860, published in tiie Proc. Bost. Soc. 

 Nat. Hist., vol. vil. p. 369. 



t Tiie Calciferous does not e.xist at Piiillipsbur^h. Billings took the Phillips- 

 burgh group, wliich corresponds to the Point Levis group, for the Calciferous 

 of Chazy Village, a synchronism wliich cannot be maintained after a visit to 

 the two places. — J. M. 



