156 ROYAL SOCIETY OF CANADA 
by-gone times littoral conditions existed. Remains of Scolithus 
Canadensis, Billings, a worm-burrow peculiar to this formation oceurs 
plentifully at Ste. Anne. No Cambrian types of fossils have been 
detected in the Potsdam of the Montreal district. 
The Calciferous formation.—Whereas the Potsdam formation lies 
unconformably over the irregularly rounded surfaces of the Laurentian 
complex beneath it, the Calciferous formation rests directly or perfectly 
conformably upon the sandstones of the Potsdam formation without any 
break whatever. At Ste. Anne, opposite the Grand Trunk railway 
station, as well as east of the village and at the north-west corner 
of Isle Jésus, Isle Bizard, at St. Eustache, and near Chateauguay, out- 
crops of this formation occur and constitute, all told, a series of strata 
probably not less than 250 feet in thickness. The Calciferous formation 
consists of dark gray, buff-weathering, more or less compact, impure 
and earthy, but at times somewhat semi-crystalline limestones, usually 
magnesian, and holding numerous cavities lined with crystals. The 
lower beds of this formation assume an arenaceous character. ‘I'ne 
limestone beds which crop out immediately north-west of the railway 
station at Ste. Anne, contain quite an assemblage of fossil organic re 
mains, amongst which may be mentioned the following species eminently 
characteristic of this horizon which indicates the second fauna of Bar- 
rande, or Ordovician system:—Pleurotomaria calcifera, P. Canadensis, 
Orthisina grandeva, Ophileta complanata, O. disjuncta, Hormotoma 
Anna, Metoptoma simplex, Orthoceras Lamarcki, Amphion Salteri, 
Bathyurus Cybele, Ribeiria caleifera, Leperditia Anna. In a small cut- 
ting along the C. P. R. track just north of the Grand Trunk Railway 
station at Ste. Anne, several minor dislocations appear which affect 
the strata at this point, and all probably owe their origin to pressures 
developed during the emanation of the volcanic masses which formed 
Mount Royal and other similar hills in the district. 
The Chazy formation.—Overlying the Calciferous formation con- 
formably at Bord a Plouffe, Terrebonne, Caughnawaga, Sault au 
Récollet, St. Martin, and on the north-east corner of Mount Royal, the 
light and dark gray semi-crystalline and at times impure fossiliferous 
limestones of this formation may be studied to advantage. The upper 
beds have yielded excellent building stone for some of the finest resi- 
dences in the city, and are of the same age as the limestones of the 
Ross quarry at Little Rideau in Eastern Ontario. 
Between 200 and 300 feet of beds probably constitute the normal 
thickness of the Chazy of Montreal. The upper limestones prove to 
be highly fossiliferous and have yielded from the vicinity of Montreal 
many types new to science which were described by the late dis- 

