552 PEOCEEDINGS OF THE GEOLOGICAL SOCIETr. [Feb. 23, 



the present instance, it extends the range of a new or little-known 

 formation, or has some other special geological interest. 



It is now several years since M. Barrande began to lay stress on 

 the most ancient of his Bohemian formations, and to draw strong 

 lines of demarcation between what he called his Faune primordiale 

 and all the succeeding faunae of the Silurian series ; and further in- 

 vestigation, either by himself or other naturalists, has only tended to 

 confirm the distinctness of this lower zone, and to show a marked 

 similarity in the types which characterize it wherever found. 



Barrande himself was the first to point out the existence of this 

 formation in the United States ("Wisconsin, &c.), as he had before 

 indicated it for Britain. It has since been recognized in Spain and 

 Normandy. Some few connecting links have been discovered, to 

 unite it with the great overlying group ; but, as a whole, both in its 

 contained species and genera, it remains a perfectly distinct and 

 well-marked formation, incomparably more cut off from the Lower 

 Silurian, than the latter is from the Middle or Upper portions of the 

 same system. 



Among the characteristic genera of this zone none is more con- 

 spicuous than Paradoocides, one of the largest forms of Trilobites, and 

 possessing marked peculiarities of structure. Numerous species are 

 known in Europe, but only one as yet from Britain ; and until lately 

 it was doubtful if the genus existed in America. The discovery, how- 

 ever, of the true locality for Paradoxides Harlani of Green*, which 

 occurs in great abundance in Massachusetts, has extended the true 

 range of the " primordial zone" to that region, and thus defined the 

 age of those altered rocks in which it is found ; for, though the 

 genera Olenus and Agnostus (the last certainly) do range out of the 

 Lingula-flags into the Llandeilo and Caradoc deposits, no instance 

 is known of such transgression on the part of Paradoxides or of 

 Conocejphalus, the genera on which we have now to offer a few de- 

 scriptive data. 



The Paradoxides under notice has been lately sent from Branch, 

 on the promontory between St. Mary's and Placentia Bays, New- 

 foundland; and, so far as I know, is the first Lower Palaeozoic 

 fossil discovered in the whole island. Mr. Bennett, who sent these 

 specimens to the Bristol Institution, says that it is accompanied by 

 many other fossils ; which statement we hope to see verified shortly 

 by a large consignment to London. 



The matrix is a hard, fine-grained, flinty slate. 



Paradoxides Bei^nettii, spec. nov. (Fig. 1.) 



P. maximus ; capite valde expanse, latitudine sequante longitudini corporis, an- 

 giilis in auriculas magnas productis, spinisque brevissimis : axi corporis latis- 

 simo, pleurarum apicibus foHosis, curvatis, vix reflexis. Long, et lat. 10 unc. 



The largest of all known species of the genus, this Paradoocides is 

 easily distinguished from the other great Trilobites, P. s^inosus, P. 



* At Braintree, ten miles south of Boston. — Prof. W. B. Rogers, Proc. Amer. 

 Assoc, vol. iii. 1856, p. 315 ; and Boston Nat. Hist. Soc. Proceed, vol. vi. pp. 27, 40. 



