36 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [FoZ.VJ.. 



tilliform genera or subgeuera, Horl-elia and Ivesia, the former of which 

 might rather be ranked among the exclusively Pacific types. A single 

 Accena is one of the Chilian forms which has reached California. Wald- 

 steinia, on the Atlantic side, is an Old World type. 



PoME^. — The amphigaean genera or groups, Cratcegus, Malus, SorhuSy 

 AmelancMer, extend across the continent at the north, one Sorbus in th© 

 very same species ; only Cratcegus on the Atlantic side displays a con- 

 siderable number of species; and the AdenoracMs group is peculiar to 

 the latter district. Seteromeles, of Asiatic type, is confined to the coast 

 of California. Feraphyllum is a peculiar shrub of the western verge of 

 the Great Basin. 



Oalycanthace m. — Are all Korth American, except the single GM- 

 monanthus of China; two species qf Galycanthus peculiar to the Atlantic 

 flora, one to that of California. 



Saxipragace^. — ^An order hardly inferior to Eosaceae in extent, in 

 amount of diversification, and in wideness of distribution. Of the am- 

 phigaean types, headed by Saxifraga, it is unnecessary to discourse, ex- 

 cept to mention that noble and most peculiar Californian species S.peltata, 

 The peculiar North American genera are, on the Atlantic side, Svili- 

 vdntia and Decjimaria ; of the Kocky Mountain flora, Jamesia, and far- 

 ther south, Fendlera; of the Pacific flora, Leptarrhena, Tolmicea, Bolan- 

 dra, Suclcsdorjia, Carpenteria ; of the Eocky Mountain and Pacific floras 

 in common, Tellima, Whipplea ; of the Atlantic and Pacific floras, but 

 not in the intervening, BoyMnia ; of all three floras, HeucJiera ; of all 

 three northward, with extension merely into Northeastern Asia, Tiar- 

 ella and Ilitella, also, with intervening species fairthersonth, PMladelphus. 

 Then, Astilbe, Hydrangea, and Itea are genera strictly divided between 

 the Atlantic flora and that of Himalaya-Japan. In Lepuropetalon we 

 have the rare case of a species peculiar to the Atlantic and the Chilian 

 floras, with no known connection. The genus Bihes assumes its max- 

 imum development and fullest diversification in North America and on 

 its western borders. Even with the alpine species included, Saxifraga is 

 comparatively weak in this country. 



CRASSULACEiE. — The amphigteau genera Tillcea and Sedum are not 

 largely represented in North America. A Mexican group, Bcheveriay 

 extends well north along the Pacific coast, but is wanting in the inte- 

 rior. Diamorpha, an unique genus of a single species, allied to Sedum, is 

 of the Atlantic flora. Penthoricm, equally peculiar, is of a single species, 

 restricted to the Atlantic States and to China and Japan. 



Deoserace^. — Appear to be absent from the whole Eocky Mount- 

 ains, except in the cool regions far north ; the Pacific flora northward has 

 the two common amphiggean species ; the Atlantic flora has four pecu- 

 liar species, and also rejoices in Dioncea. 



Hamamelide^. — Are divided between Atlantic North America, South 

 Africa, and Asia (to which most of the genera and species belong) ; our 

 single Hamamelis does not cross the Mississippi; the monotypic Fotlier- 



