482 HISTORICAL GEOLOGY. 



ceras and Cyrtoceras ; among Ti-ilobites, the genera Olenus, Agnostus, Asaphus^ 

 Ogygia, Conocoryphe, Cheirurus; and the Caridoid Entomostracans, Cera- 

 tiocaris and Lingidocaris. 



Oldhamia, from the Bray Head region, Ireland (Figs. 589, 590), has been 

 supposed to be a seaweed, and also Hydrozoan. It is stated by Dr. Kinahan. 

 to be only inorganic markings. 



In Scandinavia, where the Olenellus zone was first shown to be the true 

 Lower Cambrian by Dr. A. G. Xathorst, the Lower beds occur at Andrarum 

 in Scania beneath Paradoxides beds. They are also found near Lake Mosen 

 in Norway, and in Esthonia in Russia. They have afforded, besides Olenellus 

 Kjerulji, species of Lingulella, Obolus, Discina {?), Hyolithes, Metoptoma, 

 Scenella, and also impressions which, as stated above, page 479, are referred 

 by Nathorst to Medusae and called Medusites. The Middle Cambrian 

 beds near Kongsberg, Norway, contain Paradoxides Tessini, P. Forchhammeri^ 

 Agnostus Kjerulji, with Protospongia ; and in Sweden, the same species of 

 Olenellus with Paradoxides beds at a higher level, and above these Olenus 

 schists and Dictyonema shales. 



The Cambrian beds of Norway are very thin, the beds near Kongsberg 

 being 60 feet thick; in Sweden, the thickness is 2000 feet. The Eophyton 

 sandstone lies beneath the Olenellus beds in Norway and contains the am- 

 biguous Eophyton with Hyolithes levigatus, and worm and other doubtful 

 markings. Nathorst supposes the Eophyton to be the casts of trails of 

 Medusites. 



In Bohemia, the region of Barrande's discoveries, — an area about Prague 

 having Archaean rocks around it except on the north and northeast, — the 

 " Primordial zone," his stage C, 300 to 400 yards thick, afforded him the 

 genera of Trilobites, Paradoxides (12 species), Agnostus (5, among them A. 

 Rex, Fig. 592), Conocoryp>he (4), Ellipsocephnlus (2), Hydrocephalus (2)^ 

 Arionellus (1), Sao {Sao hirsuta, Fig. 594) ; also five species of Cystoids, with 

 species of Orthis, Orbicida, and five of Hyolithes. From the underlying beds 

 of stage B (which rest on the Archaean, stage A), consisting of slates, 

 quartzytes, schists, etc., Barrande reported traces of Annelids, Arenicolites. 

 Barrande represents the rocks in a section across from northeast to south- 

 west as lying in a simple synclinal, with an elevation of conformable Upper 

 Silurian strata at the center of the synclinal. 



On Sardinia occur Cambrian beds, from which Meneghini described, in 

 1888, two species of Paradoxides, several of Olenus, and Conocephalites, with 

 others of A^iomocare and Asaphus. No species of the Olenellus horizon 

 were reported. J. G. Bornemann described from Sardinia, in 1892, Trilobites 

 of the new genera Olenopsis, Metadoxides, and Giordanella, with Gastropods 

 of the genera Capulus, Bellerophon, and probably Carinaropsis. 



In the province of Sian-tung, China, Cambrian fossils were gathered by 

 von Richthofen, and identified by Dames as belonging to the genus Doro- 

 pyge, and referred to the age of the Quebec group. Walcott refers them to 

 the genus Olenoides, and to the age of the Middle Cambrian. 



