36 BULLETIN UNITED STATES GEOLOGICAL SURVEY. Wol.Vl. 



tillitbrm genera or subgenera, BfarkeUa and Iresia, the former of which 

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

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

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



P< »mi;.k. — The ampin ga-an genera or groups, Crataegus, Mains, Sorbus, 

 Amelanchier, extend across the continent at the north, one Sorbus in the 

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

 siderable nnmlxr of species; and the Adenorachis group is peculiar to 

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

 of ( Jalifornia. Peraphyllum is a peculiar shrub of the western verge of 

 the Great Basin. 



Calycanthace <e. — Are all North American, except the single Chi- 

 monunthus of China; two species of Calycanthus peculiar to the Atlantic 

 flora, one to that of California. 



SaxifragacetE. — An order hardly inferior to Bosacese in extent, in 

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

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

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

 The peculiar Xorth American genera are, on the Atlantic side, Sulli- 

 vawtia and Decumaria ; of the Pocky Mountain flora, Jamesia, and far- 

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

 dra. Sucbsdorjia, Carpenteria ; of the Pocky Mountain and Pacific floras 

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

 not in the intervening, Boykima ; of all three floras, Henchera; of all 

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

 ella and Jlitella, also, with intervening species farther south, Ph Uadelphus. 

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

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

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

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

 imum development and fullest diversification in North America and on 

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

 comparatively weak in this country. 



Crassulace^e. — The amphigsean genera Tillcea and Sediim are not 

 largely represented in North America. A Mexican group, Echeveria, 

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

 rior. DkunorphO) an unique genus of a single species, allied to iScduni, is 

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

 restricted to the Atlantic States and to China and Japan. 



DboSEBAOEJB. — Appear to be absent from the whole Pocky Mount- 

 i the cool r >gion - far north : the Pacific flora northward has 

 the two common amphigaean species; the Atlantic tlora has four pecu- 

 liar species, and also in Dioncea. 



Hamamki.ii>i:.i;. — Are divided between Atlantic North America, South 

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



single Hamameli8 does not cross the Mississippi; the monotypic Fother- 



