Climate of Middle Illinois. 73 



in number south westward, and so do the Onagraceae. In Colorado we 

 find the Saxifragacea3 and Polygonaceae amongst the prominents, the lat- 

 ter chiefly by the numerous species of Eriogonum, of which sixteen are 

 reported from that state, and the like number inhabit the Rocky 

 Mountains. 



The floras of the Northern States (Gray) and Southern States (Chap- 

 man) west of the Mississippi compared in the same way show the follow- 

 ing figures: 



N. Sts Composit£e 122 Cyperaceae 104 Graminese 75 Leguminosse 41 



S. Sts Compositse 148 Cyperaceae 92 Gramineffi 71 Leguminosse 54 



N. Sts Rosacese 31 EricacetB 28 Liliacese 24 Filices 24 



S. Sts LabiatEB 27 Serophulariaeefe.. 25 EricaceiB 24 Liliacese 24 



N. Sts Orchidacese 23 Scrophulariacese.. 22 Ranunculacete 21 Labiata 21 



S. Sts Rosacete 22 OrchidaceiB 21 Filices 20 Kanunculaeese 19 



N. Sts Cruciferae 19 Umbelliferse 16 Caryophyllacese 16 Saxifragacea? 15 



S. Sts Umbelliferse 17 Euphorbiacese 15 Onagracece 15 Caryophyllaceis 14 



N. Sts Juncacese 13 Onagracese 12 Euphorbiacese 12 Caprifoliacete 12 



S. Sts Cruciferae 14 Saxifragaceae 13 Polygonaceae 12 Asclepiadaceae 12 



N. Sts Najadaceae 12 Polygonaceae 11 Gentianaceae 10 Cupuliferae 10 



S. Sts Convolvulaceae.... 11 Gentianacece 10 Cupuliferte 10 Hypericaceae 10 



Comparing both rows, we find that the four first orders keep the 

 same rank; that the Labiatge, Scrophulariaceae, Euphorbiaceae, and Ona- 

 gracese take a higher position in the south than in the north; and vice 

 versa the Rosaceae, Filices, Cruciferae, and Saxifragaceae. In the sec- 

 ond row we miss the Juncacese, Caprifoliaceae, and Najadaceae; they are 

 replaced by the Asclepiadaceae, Convolvulaceae, and Hypericaceae, that are 

 not represented in the first row; the rest take nearly the same position in 

 both rows. 



GEOGEAPHICAL DISTKIBUTION OF OUR GENERA 



AND SPECIES. 



Those fanciful believers in centres of creation (not centres of preser- 

 vation as proposed by Bentham), rejecting any theory of descent, set a 

 great value upon the so called endemism and monotypes. As they admit 

 only of recent means of distribution, excluding all geological agencies, en- 

 demism is to them the principal proof of an originality of certain floral 

 areas. Monotypes are mostly the arbitrary make of systematists prone to 

 narrow limitations of genera or to wide limitations of species, or the re- 

 sult of an incomplete knowledge of species. Hepatica is a monotype as 

 soon as separated from Anemone and when at the same time we join as 

 varieties with the species H. triloba the little defined species, that have been 

 proposed; but as soon as the latter be acknowledged as species, the genus 

 would cease to be a monotype. Pentachaeta was a monotype when Nuttall 

 proposed it, but Gray decribed a second species and joined another mono- 

 type Aphantochaeta; so both of them ceased to be monotypes. Such ex- 

 amples are many; only from the order compositae may be mentioned: Cor- 

 10 



