42
are not so ~lrong|y expressed or invariable as is demanded ol horizon tltfllx'tft'x two of the brauhiopods, chlwna rliomboidalis and Atrwa retituluris are wihtont any stratigraphir value. and therefore cannot be rnnsidered Accordingly. we have only the following lelt tor purposes of
correlation: 7
Tliecia sirimlerunmm GoLnr.
(‘Iotlopnro rcctilinea/a Sun’s.
liypirlzllu cov‘I/muueusis prognosticu Senora-tam: Spirifer I‘lllt14.tl'tlti HALL vat: prognostich ScHuanar, Iioa'oneutu [ilclii HALL.
Of these Tlieciu sn‘inderelmmi is a very widespread tormt cited from the Wenlock at Northern Europe and from the Niagara” of North America [MichiganY Tennessee-L It was found. however, by Professor Krcn ol Christiania Univers y occurring in the Norwegian Silurian in rocks at>o ot relathety high Ludlow age, in other words, it seems to he stratigraphirally no greatly restricted tossit. If we consider the other tour torms. we are dealing with species that as {or as is vet known.
have a very limited vertical di nbutioiL occurring in the horizon that is the large new monograph ot the Maryland Geological Survey. “The Lower Devonian of Maryland" is called the Keyser member of the 11 e I d e r h e r; g r o n p at that state and which corresponds to the Decker Ferry»Rondout-Manlius of New Jersey and the [Wilbur- ttosendate‘fl-(Iobte. ill-Rondont-Manlins 0t eastern New York The three lll‘sl mentioned of these tour forms are very common in and
typical of this horizon. As mentioned in the dos ptive portion at this paper I have had an opportunity otrompaiing my Arctic specimens with Mo: tnrthermore been controlled by [’rote ‘ 'or Scimunzn'r, who knows the fauna
oi lilt' Ker
strongly supports this conclusion that we are dealng with an horizon
l:\ii<l-.~p€cilileiis ot three of these forms and the i entitications have
er in detail The nccm enre of certain other at our forms
rorrespomling to "IUM‘ above mentioned. The Slenochisma ot the Elles- meretantl-tauna approaches Mt closely to S. dcckermlsis WELLER, from the net:
>iinply regard it as a nothern representative oi this form, The same
er Ferry of New Jersey and the Keyser of Maryland. that I
may be said ot the variety of Spiri/er modestus, a form belonging to the mosl‘typiral l{e}'>9t'-s[lk‘t'les.
\Ve have lltth reached an important result. in heng able to correlate ~ at any rate a greater part of — the Series B with a well-known hori- zon on the Ameriran Continent. It is not astonishing to find that only
