I9I5- ^O. 12. THE STROPHOMENIDAE OF THE KRISTIANIA REGION. I07 



Relation of the Strophomenids of the Kristiania Region 

 to those of some Foreign Countries. 



As I have already commenced the study of the Strophomenids of a 

 large Russian collection I will not on this occasion go into detail as to 

 the relation of the Norwegian Strophomenids to those of other European 

 regions. A few facts only may be mentioned preliminarilv. 



As is well known the Norwegian faunas of old middle Ordovicic 

 time show a ver}- great relationship to corresponding faunas from Western 

 Russia. If we consider the Strophomenids onlv. we find a quite remark- 

 able likeness when comparing the zones 3 c '] — y of Norway with B III 

 of the Baltic provinces. Of the 5 species from 3 c, that are determined 

 as to species, no less than 4 occur in B III of Western Russia. Of younger 

 common t\-pical species might be mentioned forms like Raf. pscudoalteruaia, 

 R. l?"» scmipatiita, Stroph. pseudodtltoidca, that in Norwav occur in 5 

 (especially 5 al, in Western Russia in L3-ckholm. FI. and adjacent beds. 



In high Ordovicic and Siluric time the faunas of the Kristiania region 

 show much alfinit}' to British ones, a fact that has on several occasions 

 been emphasized by Prof. Kiær. As will be understood, a large number, 

 23, of the Norwegian Strophomenids are found in identical or closely re- 

 lated species in the British Isles, and of these 23 forms 18 do not occur in 

 older beds than stage 5, furthermore 4 (in total 22) not below the middle 

 of stage 4. The Strophomenids of 3 c and the lower half of 4 show ex- 

 tremil\- little in common with the British faunas. 



With regard to the relation to North American Strophomenids we generally 

 find very slight likeness. Only the faunas of the most Eastern part of the North 

 American continent, — best known from the Anticosti Island sections, — show, 

 as is well known, a typical European aspect, also as regards the :::>trophomemdae. 

 In the Richmondian Series of Anticosti M we meet Stroph. f.iictuosa Bill. 

 which is very closely related to our 5. pseiidodeltoideo Stoll. and from the 

 younger Gamachian Series is cited Schuchertella pecten, that in the Kristi- 

 ania region appears in 5. This form, known from stages 5 — 8, occurs 

 furthermore in Anticosti through the Becsie River, Gun River and Jupiter 

 River formations of the Siluric. Of the other common forms I /.<-/>/. rhomb. 

 and Pled, transvcrsalis not taken into consideration! we have Brachy prion 

 philomcUwi from Gun River and Jupiter River, in Norway occurring in 

 the typical shape in stage 7. Also Stroph. antiqiiata is cited from these 

 two formations and so is Tnplecia itistdoris var. aiiticostiensis, that in Nor- 

 way occurs in stage 6. 



' See Twenhofel: The .Anticosti Island faunas. 



