OF ARTS AND SCIENCES. 317 



" ' In Great Britain we know, according to the papers of Mr. 

 Salter, that Paradoxides has been found in the Trappean group (Lin- 

 gula flags of the Survey), which is the oldest fossiliferous rock o^ 

 Wales, resting on the azoic sandstones of Harlech and Barmouth. 

 There is therefore a perfect agreement in these three regions as to 

 the geological horizon of the genus now under consideration. This 

 agreement acquires still further importance from the affinities dis- 

 played equally and everywhere by the other types which accompany 

 the Paradoxides ; for instance, in Sweden we have Olenus and Cono- 

 cephalites ; in England, Olenus as recognized in the Trappean 

 group.' 



" As thus the genus Paradoxides is peculiar to the lowest of the 

 paleozoic rocks in Bohemia, Sweden, and Great Britain, marking the 

 primordial division of Barrande and the Lingula flags of the British 

 Survey, we shall probably be called upon to place the fossil belt of 

 Quincy and Braintree on or near the horizon of our lowest fossiliferous 

 group ; that is to say, somewhere about the level of the primal rocks, 

 the Potsdam sandstone, and the protozoic sandstone of Owen contain- 

 ing Dikelocephalus in Wisconsin and Minnesota. Thus for the first time 

 are we furnished with data for fitting conclusively the paleozoic age 

 of any portion of this tract of ancient and highly altered sediments^ 

 and, what is more, for defining in regard to this region the very base 

 of the paleozoic coluinn, and that too by the same fossil inscriptions 

 which mark it in various parts of the Old World. 



" Referring to the occurrence of Paradoxides in the protozoic rocks 

 of Europe, Barrande observes : ' The presence of this genus has not 

 been satisfactorily proved in any other Silurian region, although this 

 generic name has been applied to North American forms, such as 

 Paradoxides Boltoni, P. Harlani, &c. The first of these is known 

 to be a Lichas, and we know nothing of the others. The care with 

 which J. Hall has described the trilobites of the Lower Silurian 

 rocks of the country in question, is sufficient proof that he had not dis- 

 covered any trace of Paradoxides at the time of publishing the first 

 volume of the Paleontology of New York.' I may add to this, that in 

 no subsequent publication have I seen any reference to the findino- of 

 fossils of this genus in the rocks of North America. 



" One of the most curious facts relating to the trilobite of the 

 Quincy and Braintree belt is its seeming identity with the P. Harlani 

 described by Green in his Monograph of North American Trilobites. 



