Climate of Middle Illinois. 73 



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

 find the Saxifragacese and Polygonacese 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 Compositse 122 Cyperaceae 104 GramineaB 75 Leguminosae 41 



S. Sta Compositae 148 Cyperaeeee 92 Graminese 71 Leguminosse 54 



N. sts Eosacese 31 Ericaceae 28 Liliaceae 24 Filloes -...24 



S. Sts Labiate 27 Scrophulariaceas.. 25 Ericaceae 24 Liliaceae 24 



N. Sts Orohidaceae 23 Scrophulariaceae.. 22 Rauunonlaceae 21 Labiatae 21 



S. Sts RosaccEe 22 Orchidaceae 21 Filices 20 Ranunculaceae 19 



N. Sts CrucHerae 19 TJmbelliJerae 16 Caryophyllaceae 16 BaxifragaccEe 15 



S. Sts UmbellHerae 17 Euptorbiaceae 15 Onagraceae 15 Caryophyllaceae 14 



N. Sts Juncacese 13 OnagraceaB 12 Euphorbiace^ 12 Caprifoliaceje 12 



S. Sts Cruoiferae 14 Saxifragaceae 13 Polygonaceae 12 Asclepiadaceae 12 



N. Sts Najadaceae 12 Polygonaceae 11 Qentianaceae 10 Cupuliferae 10 



S. Sts ConTolvulaceae.... 11 Gentlanacece 10 CupuliferEe 10 Hyperloaceae 10 



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

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

 graceae 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, Convolvulacese, and Hypericacese, that are 

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

 both rows. 



GEOGEAPHIOAL DISTEIBUTION OF OUE GENEEA 



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 



