MINERALS AND GEOLOGY OF CANADA. 209 
’ In the annexed section, 1 indi- 
cates the higher portion of the 
Medina beds; 2, the grey band, 
which forms the upper limit of _ 
this series ; 3, the Clinton strata; SS 
and 4, 5, and 6, the succeeding 
calcareous beds of the Niagara 
I e 1 = SSS 
formation. In the Medina de LQVJJJJFTGWJJ[{ (= 
posits, fossils are exceedingly rare. 
They appear with us to be limited 
to fucoids, and to a single species 
of lingula of a triangular or cuniform outline (Z. cuneata.) The most 
characteristic fucoid is the Arthrophycus Harlani, (fig. 211), a form 
which occurs also, and more abundantly, in the Clinton beds, These 
Fig. 210. 
latter contain, in addition, va- 
rious corals, brachiopods, trilo- 
bites, &c.; many of which, 
however, belong likewise either 
to the succeeding Niagara for- 
mation, or to some of the 
Fig, 211.—Arthrophycus Harlani (Hell.) Hudson River or Trenton beds 
of the Lower Silurian series. Some of the most abundant comprise: 
Stenopora fibrosa, (fig. 117,) Heliopora fragilis, 
(fig. 212,) Favosites Gothlandica, (fig. 214,) 
Strophomena rhomboidalis, (fig. 232,) Orthis 
lynz, (fig. 135,) O. elegantula, (fig. 218,) Spiri- 
er radiatus, (fig. 220,) Atrypa reticularis, (fig. _. : 
a and ity tie Blumenbackii, (fig. aes og edi (Hall) sh 
This formation (Nos, 9 and 10, the latter denoting the upper or 
Clinton beds, in the sketch map, figure 249) constitutes the greater 
portion of the south shore of Lake Ontario, and sweeps round the 
western extremity of the lake, by Hamilton, &c., to within a short 
distance of Oakville. From these points, it runs in a general north- 
erly and north-westerly direction through East and West Flambo- 
rough, Nelson, Caledon, &c., up to the western extremity of 
Georgian Bay, where its higher strata form the lower and middle 
portion of the promontory of Cabot’s Head. From Queenston, 
where it enters Canada, along the whole of this distance, the formation 
is capped by an escarpment or cliff-face of the succeeding Niagara 
