94 THE ROYAL SOCIETY OF CANADA 



are undoubtedly outliers of the Monteregian Petrographical Province. 

 Four of these intrusions consist of alnoites or of very similar basic 

 rocks and are situated at Como, Ste. Monique, La Trappe, and on the 

 Husereau Farm near St. Benoit, all in the Province of Quebec. The 

 fifth is a fourchite sheet from Ste. Dorothée on Isle Jesus. Two breccias 

 are also briefly described, one from La Trappe and the other from near 

 Ste. Dorothée. 



These intrusives are all very closely related to one another, with 

 the exception of the fourchite from Ste. Dorothée. This sheet-like 

 intrusion is considered to be contemporaneous with the essexites 

 of the western Monteregians of which it is the hypabyssal equivalent. 



The breccias occurring to the north of Ste. Dorothée are in all 

 probability related to the breccias described by Harvie rather than to 

 the fourchite which occurs in the immediate vicinity, and, therefore, 

 were formed later than the latter. 



The more basic intrusions together with the alnoites described 

 by Bowen from Isle Cadieux, and by F. D. Adams from Ste. Anne de 

 Bellevue, form a line roughly bordering the intrusive breccias toward 

 the west. The alnoitic intrusives are closely associated with the 

 breccias described by Harvie. The intrusive at La Trappe is undoubt- 

 edly connected with breccias nearby, and the alnoite dyke at Ste. 

 Anne de Bellevue may be associated with the neighbouring breccia. 



All of the alnoitic rocks apparently commenced to crystallize 

 out as monchiquites (that is, as olivine-augite-biotite rocks), but some 

 change in conditions of crystallization caused the partial resorption 

 of the earlier minerals and new minerals were formed; because of 

 different conditions prevailing in each locality, the later minerals are not 

 the same in each of the various occurrences. Each occurrence is itself 

 composed of several phases which may be products of magmatic 

 differentiation before intrusion as at the Husereau occurrence, or after 

 intrusion as at La Trappe, or they may be simply textural variations 

 of the principal type as at the other localities. 



Most of the rocks encountered and also some of the phases of 

 each occurrence show associations of minerals for which names have 

 not been provided in the Qualitative Classification. Following 

 Bowen's example, the writer has decided not to add any new names to 

 a nomenclature already overcrowded with names based on locality 

 rather than on the mineralogical composition of the rocks occurring 

 at that locality. 



Although these basic rocks differ slightly in their mineralogical 

 composition, they are not only related to one another and to the 

 breccias, but they also represent basic differentiation products of the 



