120 The American Geologist. August, 189* 
ian. than to the Meristas and Meristellas of the Lower Helderberg and 
Oriskany. [ndeed among the identifications we find thai of M. (Whit- 
fieldella) nitida Hall, a Niagara species. Numerous small Rhynchonel- 
las occur, of the type of /.'. wMUi&nd It. indianensis, of the Niagara; one 
large Form, Wilsonia pila, var. irbitensis, nov. is like II'. mffordi Hall. 
Ii is the pentameroids thai pul the Devonian conception to the severesl 
strain. Here we meet a remarkable developmenl of genera which one 
is wonl to regard as eminently Silurian: greal plicated Conchidiums of 
the type of P. knighti (P. pseudoknigliti, qov., P. vogulicusYem., P. 
rossicus Karpinsky, P. karpinskii, nov.. etc.); P. taltiensis, a smooth 
shelled, true Pentamerus of the ty] 1' P. pergibbosus, Hall and Whitfield 
and P. striatus Eichwald, a form which, in some of its phases, shows 
the passage of Pentamerus to shells with the completely reversed con- 
vexity <>t' the valves possessed by the recently described genus CapelUnia, 
from the Niagara dolomites of southeastern Wisconsin. This reversal 
of convexity and predominance of the brachial over the pedicle-valve 
are well shown on pi. 12, fig. .">. The type of P. linguifer Sowerby, P. 
ventrico8U8 Hall (= BarrandeUa; smooth shells with median fold on the 
brachial valve) is represented i>\ P. krasnopolskiij nov. 
Among other Silurian forms may also be counted the genus Pasceolus, 
Billings. 
Turning to the elements of the fauna which may be regarded as rep- 
resentatives of the American lower Devonian (Lower Helderberg, Oris- 
kany), we shall find them conspicuously few. Isolated species, Proefus 
uralicus, now. Orthonychia ekmgata Hall. 0. eultellus, nov.. present a De- 
vonian aspect. Schizodus .' uralicus, nov.. (hinge unknown) lias the pe- 
culiar form of Palaeoneilo leda Hall, of the Hamilton fauna. Atrypa 
sublepida Vera, has the introverted spirals of Atrypina; while it hears 
the external aspect of Codospira, The species identified as Pentamerus 
aeutohbatus Sandberger, is a similar shell to the Lower Helderberg 
species commonly identified as P. galeatus, though more sharply plicate. 
Strophomena wagranensis Gruenewaldt, is a Stropheodonta with the in- 
terplicate crenulated surface of S. varistriata of the Lower Helderberg 
and 8. patersoni of the Upper Helderberg. Orthis subcarinata of the 
Lower Helderberg is present in the Siberian fauna. More distinctively 
Devonian types are found among the corals: Amplexus, CystiphyUum, 
Diploclwru (Freeh's genus), Favosites goldfussi, F. polymorphs, Alveolites 
goldfussi. 
The determination of this assemblage as a Devonian fauna seem- the 
logical outcome of recent analytical studies of heterotope faunas, which. 
beginning with BTayser's, of the oldest fossil-bearing rocks of the Hartz 
(1878), have been productive of important modifications in the current 
interpretation of various local faunas. Kayser's detailed investigation 
of the Zorge and Wieda Schiefer of the Hartz. which A. Roemer had 
declared to lie of Silurian age, demonstrated a predominance of Devon- 
ian types; the correlations instituted by him between this fauna and 
those nf tin' Bohemian etages F, G and II of Barrande, led him to argue 
the early Devonian age of the latter also. NovAk, Katzer, Barrois, 
