XV.] CAMBRIAN AND SILURIAN IN EUROPE. 369 



* 



This classification of the ancient Bohemian faunas was first 

 set forth by Barraiide in 1846, in his Notice Preliminaire, 

 in which he declared that the first fauna was below the base of 

 the Llandeilo of Murchison, unknown in Great Britain, and, 

 moreover, " new and independent in relation to the two Silu- 

 rian faunas (his second and third) already established in 

 England." This opinion he reiterated in 1859. These three 

 divisions form in Bohemia an apparently continuous series, and 

 being connected with each other by some common species, 

 Barrande was led to look upon the whole as forming a single 

 stratigraphical system; and finally to assert that these three 

 independent faunas " form by their union an indivisible triad, 

 which is the Silurian system." (Bull. Soc. Geol. de Fr. (2), 

 XVI. 529-545.) Already, in 1852, in his magnificent work 

 on the Silurian System of Bohemia, Barrande had given to the 

 strata characterized by his first fauna the name of Primordial 

 Silurian. It is difficult to assign any just reason for thus an- 

 nexing to the Silurian already augmented by the whole 

 Upper Cambrian or Bala group of Sedgwick (Llandeilo and 

 Caradoc) a great series of fossiliferous rocks lying below the 

 base of the Llandeilo, and unsuspected by the author of the 

 Silurian System, who persistently claimed the Llandeilo beds, 

 with their characteristic second fauna, as marking the dawn of 

 organic life. 



Up to this time the primordial palaeozoic fauna of Bohemia 

 and of Scandinavia was, as we have said, unknown in Great 

 Britain. The few organic remains mentioned by Sedgwick in 

 1835 as occurring in the region occupied by his Lower and 

 Middle Cambrian, on Snowdon, were found to belong to Bala 

 beds, which there rest upon the older rocks : nor was it until 

 1845 that Mr. Davis found in the Middle Cambrian remains 

 of Lingula. In 1846, Sedgwick, in company with Mr. Davis, 

 re-examined these rocks, and in December of the same year 

 described the Lingula beds as overlaid by the Tremadoc slates 

 and occupying a well-defined horizon in Caernarvon and Me- 

 rionethshire, beneath the great mass of the Upper Cambrian 

 rocks. (Geol. Jour., II. 75; III. 139.) Sedgwick, at the same 

 16* x 



