368 CAMBRIAN AND SILURIAN IN EUROPE. [XV. 



as synonymous with Zenker's name of Conocephalus (Cono- 

 cephalites), already appropriated to a genus of insects. 



Meanwhile, the similar crustaceans which abound in the 

 transition rocks of Bohemia had been studied and described by 

 Hawle, Corda, and Beyrich, when Barrande began his admi- 

 rable investigations of this ancient fauna and of its stratigraph- 

 ical relations. He soon found that beneath the horizon charac- 

 terized by fossils of the Bala group (Llandeilo and Caradoc) 

 there existed in Bohemia a series of strata distinguished by a 

 remarkable fauna, entirely distinct from anything known in 

 Great Britain, but closely allied to that of the alum-slates of 

 Scandinavia, corresponding to Eegiones II. and III. of 

 Angelin. To this he gave the name of the first or primordial 

 fauna, and to the rocks yielding it that of the Primordial Zone. 

 Resting upon the old gneisses of Bohemia appears a series of 

 crystalline schists designated by Barrande as Etage A, overlaid 

 by a series of sandstones and conglomerates, Etage B, upon 

 which repose the fossiliferous argillites of the primordial zone, 

 or Etage C. The rocks of the Etages A and B were by Bar- 

 rande regarded as azoic, but, in 1861, Fritsch of Prague, after a 

 careful search, discovered in certain thin-bedded sandstones of 

 B the traces of filled-up vertical double tubes ; which, accord- 

 ing to Salter (Mem. Geol. Sur., III. 243), are probably the 

 marks of annelides, and are identical with those found in the 

 rocks of the Bangor or Longmynd group in Great Britain, 

 which will be shown to belong to the primordial zone. It is, 

 therefore, probable that the Etage B, which apparently cor- 

 responds to the Regio Fucoidarum or basal sandstone of 

 Scandinavia, should itself be included in the primordial zone. 

 It may here be noticed that it is in the crystalline schists of A 

 that Giimbel has found Eozoon Bavaricum. To the Etage C in 

 Bohemia, Barrande assigns a thickness of about 1,200 feet, and 

 to this his first fauna is confined, while in the succc'cdin^ 

 divisions he distinguished a second and a third. The second 

 fauna, which characterizes Etage D, corresponds to that of the 

 Bala group ; while the third fauna, belonging to the Etages E, 

 1 . < i, and H, is that of the May Hill, "Wenlock, and Ludlow 

 formations of Great Britain. 



