86 The American Geologist. August. L903, 
Quebec and near the northern line of Vermont* At the same 
time the increasing difficulty of communication in this direction 
will suffice to explain the diminishing resemblance between the 
faunas of western Europe and Appalachia. 
2. Regarding the southern connections of the Appalachian 
waters, if the view set forth in the earlier portion of this paper 
he admitted, all communication in that direction from the inner 
portion of the gulf was cut off, in days long preceding the 
Hamilton period, by the elevation that brought the Silurian 
strata successively above the water-level. This uplift closed the 
southern bight as early as the Niagara and. probably a* early as 
the Clinton period. It must therefore have isolated the fauna 
from all direct southern connection almost from the beginning 
of the Silurian era. 
Devonian Geography Southwest of Appalachia. — Further 
consideration of professor Williams's theory renders necessary 
an investigation into a somewhat wider field. It has already 
been shown that the Lower Devonian and Silurian strata came 
up successively (speaking generally) to the southward, indicat- 
ing plainly a closing of any previously existing channel in that 
direction at the end of the Ordovician era and the progressive 
reduction of the water area as the Clinton, Niagara, Lower 
Helderberg, Oriskany and Corniferous periods passed. The ev- 
idence in favor of these changes can scarcely be invalidated, 
though the minor details will doubtless be subject to some al- 
terations. It is therefore futile to look in that quarter for any 
channel of communication with a sea in the southern hemisphere 
extending over South America, the South Atlantic (Faukland 
isles) and South Africa. All passage in that direction was ab- 
solutely and, so far as we can see, continuously barred. The 
eastern shore of the gulf was certainly unbroken and the south- 
west therefore presented the only possible opening. 
About 400 miles west of the Nashville-Cincinnati promon- 
tory rises the ( )zark uplift in which the ( )rdovician and Cam- 
brian strata rise to the surface, and west of this line of outcrop, 
* The following species are mentioned from this locality in the Geology of 
Canada, 1863, p. 428, from the district near lake Megantic. 
I-avositcs gotLlandicus Syringopora hisingeri 
Favosites basalticns Dipliyphyllum artindinaceum 
Heliophyllum oncidense Orthis striatula 
Strophomcna rhomboidalis Spirilera gregaria 
Spirifera duodenaria Spirilera acuminata 
Atrypa reticularis Cy'rtina rostrata. 
