OF ARTS AND SCIENCES. 241 



of Agnostus ; ITijoUthes socialis, H. tenuistriatics, and H. pUcatus ; 

 Lingula, Ortlds, Oholella^ Ac7-othele, and Acrotreta. 



This fauna indicates the lower part of the true Primordial. But the 

 American Infra-Primordial has not yet been recognized in Norway. 



The second division (Etage 2), or " Die Olenus schiefer," with an 

 average thickness of 150 feet, is subdivided by Mr. W. C. Brtigger 

 into live parts, called 2 «, 2 b, 2 c, 2 d, 1 e. The first is especially 

 the level of the Olenus : then come the beds with Parabolina, closely 

 allied to the genus Olenus, with which it has often been confounded ; 

 then the Earycare, the Pelturn, and a schist with Dyctyonema (Grap- 

 toUtes), forming the base of the Supi'a-Primordial fauna. Beside the 

 trilobites belonging to the genera already cited, and two or three 

 others, forming a total of twenty-one species, only one Orlhis, one 

 Lingula, and one Oboliis have been found. 



It is clearly the same fauna as that of the Georgia slates, or zone of 

 Olenelhis, of America. 



In the lithology the assimilation is the same ; for in Norway the 

 slates enclose small limestone lentils, in the middle of which the fossils 

 are found by preference, just as in Vermont. 



The third division (Etage 3), or "Die Asaphus Etage" of Brogger, 

 follows that with Olenus in concordant stratification, as is shown in a 

 fine section of the railroad to Vestfosen near Christiania.* 



In this remarkable memoir, the first, or 3 a group, which is sub- 

 divided into a, j3, and y, has a mixture of primordial trilobites, with 

 forms belonging to the second fauna, resembling the deposits at Hof, 

 at Point Levis, and at Phillipsburgh. The Ceratopyge are so near 

 the Olenus, that Prof. Sars has put them in the same genus. The genus 

 Dikelocephalus^ so remarkable in Ameiica, is found in Norway in the 

 subdivision y of the group 3 a. Further, there are also Agnostus, 

 Gyclognathus, a genus allied to the Pcttura and the Olenus, and one 

 Parabolinella. On the other hand, the following genera of trilobites 

 make their first appearance : Amphion, Cheirurus, Holometopus, Har- 

 pides, Triarthrus, Megalaspis, Niobe, Symp/tysurus, and Am pyx ; all 

 belonging to genera that made their first apparition in America at the 

 same epoch. 



In this division 3, subdivision 3 a, mollusks are more rare than in 

 America ; there are only one Orthocerns, one Bellerophon ? one Orlhis, 

 two Lingula, one Lingidella, two Obolus, one Oboklla, one Discina, 



* Die Silurischen Etage 2 und 3 in Kristianiagebirt und auf Ekcr, by W. C. 

 Brijgger, p. 29 (Kristiania, 1882). 



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