58 
(From the mass.on the east side of the dyke in the 
southern exposure, belonging to the same fauna as above.) 
Favosites helderbergiz, Hall. Orthothetes, cf. Woolworthanus, 
Cf. Lichenalia distans, Hall. Hall. 
Orthis (Schizophoria) multistriata, Lepteena rhomboidalis, Wilckens. 
Fall: Camaroteechia, cf. ventricosa, Hall. 
Stropheodonta arata, Hall. Rhynchonella, li. formosa, Hall. 
Strophonella punctulifera, Conrad. Atrypa reticularis, Linn. 
Spirifer, cf. concinnus, Hall. 
Dr. Williams states that it seems quite evident from 
the critical study of the species that neither of these 
St. Helen’s Island faunas is to be correlated exactly with 
any one of the known faunas of New York or of the interior 
of the American continent. Nor do they agree exactly 
with any of the more eastern faunas of Maine, Quebec, 
New Brunswick or Nova Scotia. Nevertheless, a resem- 
blance is found for the first fauna with the Oriskanian and 
for the second fauna with the Helderbergian which they 
bear to no other faunas. 
The matrix of the breccia under the microscope is 
seen to be composed largely of carbonates, as may also be 
ascertained by treating a hand specimen with dilute acid, 
but it also contains epidote, pyrite, apatite, perovskite, zir- 
con, and, occasionally a mineral resembling hydronephelite. 
The original material is now completely decomposed. It 
was supposed by Sir William Dawson that this occurrence 
together with the other patches of breccia which occur on 
Ile Bizard and elsewhere, represented remnants of the 
ejectamenta from the ancient volcano of Mount Royal. 
This also was the view taken by Nolan and Dickson in 
their study of the occurrence. More recent investigations, 
of these other breccias, however, show that they have 
a matrix composed of camptonite, alnoite or other allied 
magmas and that the bodies have the character of intrusive 
masses. It seems probable, therefore, that the breccia of 
St. Helen’s island also represents an intrusion of similar 
magma which has subsequently been so completely altered 
that its original character can be no longer recognized. 
This explanation also accounts for the distinct peripheral 
alteration so often seen in the fragments, more especially 
the limestone fragments, in the breccia. 
The presence in the breccia of fragments of Upper 
Silurian and Devonian age has naturally been a source 
