432 THE CANADIAN NATURALIST. [Dec. 



dicotyledonous genera decreases from our section of the continent 

 southward. Thus, in Ontario and Quebec monocotyledons are to 

 dicotyledons as 1:3.46; in the Northern States as 1:3.61, and in 

 the whole of the States east of the Mississippi as 1:4.13. The 

 numerical relations of filicoid to phaenogamous genera present 

 much more marked differences. In the Provinces the proportion 

 is as 1:24, whilst in the Northern States it is as 1:28.9. 



The relative positions of the orders with respect to the number 

 of genera in them vary to some, though not to any considerable, 

 extent in the two countries. In the Northern States and the 

 whole Union these relative positions are not much different. 

 Composites and Graminae, however, assume the precedence there 

 in each case as well as here. Arranging the large orders repre- 

 sented in each country according to priority in point of number 

 of included genera, the following results are presented : 



In Oti'ario and Quebee- 



Composite 56 Filices, Liliaceae and Umbellifeae, each 19 



Graminae 47 Cruciferae and Rosacea?, " 17 



Labiatae 24 Ranunculaceae and Scrophulariaceae, " 15 



Ericaceae 22 Orchidaceae 14 



Leguminosae 21 Caryophyllaceae 12 



In Northern States. 



Compositae 86 Umbelliieraeae 27 



Graminae 67 Scrophulariaceae 25 



Leguminosae 39 Filices 22 



Labiatecleae 33 Ranunculaceae and Cruciferae, each.. . . 20 



Liliaceae and Ericaceae, each 28 Rosaceae 18 



Of the 576 genera in the two Provinces, 291 or rather more 

 than one-half, are referable to the twelve orders which take 

 precedence in the first of these lists. The aggregate of the 

 genera in the second list barely attains the half of the whole 

 number of genera which have representatives in these States. 



The largest interest is of course invested in the species which 

 occur within our geographical limits, and in the numerical 

 relations of the orders and genera with regard to the species 

 which they embrace. The details given with respect to them 

 will be less wearisome. 



Recent discoveries have confirmed the occurrence in Canada of 

 several species whose previous claims to a place in our flora rested 

 solely on the authority of Michaux or Pursh. I have therefore 

 experienced a reluctance to exclude any of their species — unless 

 the occurrence of the plant is very improbable — on the mere 

 ground that it has not been noticed by subsequent observers. 

 This reluctance is increased by the circumstance that the Lake 

 Superior and lower St. Lawrence districts, where many, if not 



