Letters of Mr. Brongniart, with remarks. 225 



resemblances so striking, that often it would not be possible 

 in a collection, to distinguish a psammite* or a compact 

 limestone which came from England, from one, from the 

 environs of Vienna or of Rome, provided the labels did not 

 give us information as to the different places. 



" We are certain of these resemblances, as to all the coun- 

 tries of Europe, and from indications sufficiently clear, we 

 presume them for Asia, Africa, America and the islands. — ■ 

 It remains to establish them in a manner evident and cer- 

 tain, and to prove that they exist at such great distances. 



" It is for you sir — it is for the numerous and well inform- 

 ed geologists, who inhabit the greater part of the American 

 states, to follow up these observations, and to put it in our 

 power to compare, with precision, the American formations 

 with ours ; with this view I have already sent to you, and to 

 other American naturalists, and I will continue to forward, 

 suites of European Rocks. 



"You have also transmitted those that were, in this 

 point of view, very interesting, and which I have already 

 had the honour to acknowledge. 



" I ask the continuance of these interesting relations, so 

 useful to the sciences and to true philosophy and so hon- 

 ourable to myself. 



"I have just terminated a work which I began five years 

 ago, upon a family of organized bodies, called trilobites. — 

 I received the last year, from the Royal Academy of Sci- 

 ences, an impression in plaster, of an American trilobite 

 sent to the academy by Dr. David Hosack of New-York, and 

 which came from the region of Albany. I pointed out in 

 my report, the similiarity between the formations in which 

 this fossil was found and those in England, France, Sweden 

 and other countries of Europe, where the same animal re- 

 mains have been found, but at first, I could not establish any 

 difference between that of M. Blumenbach and that of M. 

 Hosftck, — the plaster cast which represented the latter, 

 vmaso ill defined, that no exact judgement could be passed 

 upon the differences or resemblances. 



"In repeating these observations, and comparing again, 

 this impression with two other specimens of trilobite, one of 

 which also, came from America, they were united by Mr, 



* A micaccoijs sand stone (in Mr, Brongniart's nomenclature,) 

 Vol, III.....N0, 2, -29 



