TWENHOFEL: EXPEDITION TO THE BALTIC PROVINCES. 339 
tion is hence made with greater confidence. It is also possible that 
the upper beds of the St. Johannis formation have an equivalence 
with the Lower Ludlow of England. 
As is to be expected, the case is not so sharply clear for the American 
sections; but no less than twenty species occur in the American 
Niagaran ! or are represented by forms closely related. These are: — 
Hindia fibrosa. 
Cystiphyllum cylindricum. 
Favosites gothlandicus. 
hisingeri. 
Halysites catenularia. 
Paleocyclus porpita. 
Atrypa reticularis. 
Cyrtia exporrecta. 
Dalmanella elegantula. 
10. LEospirifer radiatus. 
11. Leptaena rhomboidalis. 
12. Meristina tumida. 
13. Plectambonites transversalis. : 
14. Rhipidomella hybrida. 
15. Rhynchotreta cuneata. 
16. Schuchertella pecten. 
17. Spirifer crispus. 
18. Wilsonia wilsoni. 
19. Calymene tuberculata. 
20. Encrinurus punctatus. 
oe a ee SE 
There is little doubt that the above list will be lengthened when 
the St. Johannis fauna has been comparatively studied. Heliolitidae 
are present which are quite similar to the American species and such 
is the case with other forms of other groups. Since the fauna has by 
no means been carefully studied, only a few over fifty species having 
been recognized, this makes over thirty per cent of the fauna which 
has been recognized in the American Niagaran. It is also possible that 
the St. Johannis formation extends a little higher than the highest 
beds of the Niagaran. 
In the Anticosti section the formation may find representation in 
the upper portion of the Jupiter River formation and almost certainly 
in the Chicotte, but the Anticosti series does not extend high enough 
to completely represent the Russian formation. 
1 Niagaran as here used excludes the Clinton. 
