1915- ^«-^ 12. THE STROPHOMEMDAE OF THE KRISTIANIA REGION. IO9 



verv' few points ot* connection. From what can be judged from the pre- 

 sent investigation, the equivalent of the Trenton must extend rather far 

 down in 4. as already in 4 b representatives of forms are found, that in 

 America are not known below the Trenton, e. g. Leptaena rhotnboidalis, 

 Raf. deltoidea and PîectainbomteS'Spçc\m€:r\5 that belong to or come very 

 near to Pled, sericea. 



Of Siluric forms that are identical or closely related we have Stroph. 

 costatula Hall and Clarke, from stage 6 of Norway and the Niagara 

 of America iKentuckyi. Of interest is the occurrence of a form which I 

 consider closely related to the Raf. expansa, which has its main occur- 

 rence in 6, viz. Strop lie odanta corrugata Conr. from the Clinton of 

 New York and other states. A form that finally reminds us somewhat of 

 Sckuchertella pecten from 5 — 8. is S. subplana Conr., especially common in 

 the Niagara. 



