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quarry in the Beauharnois dolomite. On the right hand 
-border of the quarry, some fossils can be found in place, 
but more and better specimens can be obtained from the 
loose pieces of rock which are scattered about. This is 
the typical locality for Hormotoma anna, Leperditia anna, 
Holasaphus mooret, and other species. 
The Potsdam can also be examined at this point. In 
I9QI2 a sewer excavation on the street exposed both the 
Beauharnois dolomite and the Potsdam, though the 
contact between the two was concealed. The Potsdam 
here is hard and quartzitic, and there are none of the soft 
transitional layers usually seen between the Potsdam and 
the equivalent of the Beauharnois farther west. 
St. HELEN ISLAND. 
Fosstliferous Lower Devonian Limestone in an igneous 
Breccia.—Utica shale occupies the southern end of St. Helen 
island. The shale is cut by several dykes and is somewhat 
altered, so that it is more friable than is usual. Close to 
the dykes there is usually a narrow band of rock which 
has been altered to hornstone. 
On the eastern side of the island is exposed the breccia 
which occupies the larger part of the island. This rock 
is composed of angular and rounded fragments of red and 
black shale, hornstone, limestone, red and gray sandstone, 
granite, gneiss, and quartzite. The fragments are imbedded 
in a fine-grained matrix of igneous origin which wea- 
thers to a reddish brown. 
At the north-eastern end of the island, near the swim- 
ming pool, are large fossiliferous blocks of gray, coarse- 
grained limestone. The most northern and largest of these 
blocks contains an Oriskany fauna, with Spirifer arenosus, 
S. montrealensis, Eatonia peculiaris, and many other fossils. 
A smaller block to the east of this contains a Helderbergian 
fauna with Suiberella pseudogaleata, Spirifer concinnus, 
Leptena rhomboidalis, Stropheodonta becki, and _ other 
species. The general facies of these faunas is much more 
like their equivalent in Gaspe than in New York. 
No strata of Helderbergian or Oriskanian age occur 
anywhere in this region, but from the presence of these 
blocks in the breccia, it is believed that such strata once 
extended over this area. The presence of the blocks is 
explained upon the theory that they were stoped off from 
