il! OLAF HOLTEDAHL. [SEC. ARCT. EXP. FRA.M 



are not >o strongly expressed or invariable as is demanded of horizon 

 maker-, two of (lie brachiopods, Leptcvna rhoniloidaUs and Atryjxi 

 i-rliciilui-ix arc wihtout any stratigraphic value, and therefore cannot he 

 considered. Accordingly, we have only the following left for purposes of 

 correlation : - 



Thecia swinderenana GOLDF. 



ciailopora rcdilineata SIMPS. 



Gyjiiiluld coi'jimanensis proguostica SCHUCHERT. 



Spirifer ranuxcmi HALL var. prognostica SCHUCHERT. 



Loxonema fitch i HALL. 



Of these Tliecia srvinderenana is a very widespread form, cited 

 from the Wenlock of Northern Europe and from the Niagaran of North 

 America (Michigan, Tennessee). It was found, however, by Professor 

 KI.KR of Christiania University occurring in the Norwegian Silurian 

 in rocks also of relatively high Ludlow age, in other words, it seems to 

 be stratigraphically no greatly restricted fossil. If we consider the other 

 four forms, we are dealing with species that as far as is vet known, 

 have a very limited vertical distribution, occurring in the horizon that is 

 the large new monograph of the Maryland Geological Survey, "The 

 Lower Devonian of Maryland" is called the Keyser member of the 



/ / 



H e 1 d e r b e r g group of that state and which corresponds to the 

 Decker Ferry -Ron dout -Man lius of New Jersey and the (Wilbur- 

 Rosendale?)-Cobleskill-Rondout-Maiilius of eastern New York. 

 The three first mentioned of these four forms are very common in and 

 typical of this horizon. As mentioned in the descriptive portion of this 

 paper I have had an opportunity of comparing my Arctic specimens with 

 Maryland-specimens of three of these forms and the identifications have 

 furthermore been controlled bv Professor SCHUCHERT, who knows the fauna 



J 



of the Keyser in detail. The occurrence of certain other of our forms 

 strongly supports this conclusion that we are dealing with an horizon 

 cnrre-pi Hiding to those above mentioned. The Stenocliisnia of the Elles- 

 mereland-fauna approaches so closely to . deckerctisis WELLER, from the 

 Decker Ferry of New Jersey and the Keyser of Maryland, that I 



/ /' 



.simply regard it as a nolhern representative of this form. The same 

 may he >aid of the variety of Spirifer inodestus, a form belonging to 

 the most-typical Keyser-specie-. 



\Ye have thus reached an important result, in being able to correlate 

 -at any rale a greater part of- the Series B with a well-known hori- 

 zon on the American Continent. It is not astonishing to find that onlv 



