48 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [Tol.Yl. 



Laueace^. — Mainly tropical or subtropical all around the world^ 

 yet there are three genera in the Atlantic flora (one, Sassafras, a fine 

 tree, and all of Asiatic affinities) and a peculiar one in California. 



Thymel^ace^. — Most developed in the southern hemisphere. In 

 North America is only Dirca, one species in the Atlantic flora, the other^ 

 very local, in the Californian. 



EL^AGNACEiE. — Two of the three genera of this little order are North 

 American. The two species of Shepherdia nearly traverse the continent 

 at the north, and a third species has been discovered on the southern 

 rim of the Great Basin. An Elceagnus belongs to Eocky Mountain region, 



LoRANTHACE^. — Are represented by two genera, allied to Yiscum. 

 Phoradendron is peculiar to America. The common species in some its of 

 forms traverses the continent ; another belongs to the Californian dis- 

 trict and adjacent parts ; the others are more southern. Arcewt,hobium 

 is amphigaean, of three or four American species, mostly Pacific or south- 

 ern, one sparingly represented in the Northern Atlantic States. 



SantalACE^. — Aie most largely of the southern hemisphere. The 

 distribution of our four genera is interesting. Gomandra consists of a 

 European species, two North Ameiican ones, which traverse the conti- 

 nent northward, and a fourth, which belongs mainly to the Eocky 

 Mountain region southward. Buckley a consists of an Atlantic (Alle- 

 ghanian) species and one in Japan ; Darhya of a single and local Atlan- 

 tic species, of some ambiguity, because the female plant is unknown ; 

 Pyrularia of an Alleghanian species and a Himalayan. 



EuPHORBiACE^. — An immense order of 3,000 species and, at the least^ 

 200 genera. The world-wide and j)roliflc genus EupliorMa is very mod- 

 erately represented in the Atlantic flora, sparingly in the Pacific, numer- 

 ously in the drier parts of the intermediate country, especially south- 

 ward. The other large and non-peculiar genera are mainly southern in 

 range. Peculiar genera are very few — JEremocarpus in the Pacific flora ;, 

 Crotonopsis in the Atlantic. Of the Buxinece, there is Simmondsia on the- 

 Californian coast, of n*o near affinity : Pachysandra, in the AUeghanies, 

 which has a congener in Japan. 



Empetracbje. — Have all three genera in the Atlantic flora, and not 

 elsewhere — JEmpetrum alpine and northern ; Corema on the coast of the 

 United States, the other species on the opposite Atlantic coast in Por- 

 tugal 5 Ceratiola in the Southern Atlantic States. 



Ceratophylleje. — Probably of a single species, amphigaean, both 

 Atlantic and Pacific. 



Urticace^. — Taken in the large sense, may be referred to under 

 their suborders. 



TJrtice^. — Are few on either side of the continent, nearly absent 

 from the Eocky Mountains and Great Basin, an TJrtica or two, and the 

 same of Parietaria ; Hesperocnide is divided between California and the 

 Hawaiian Islands ; Laportea, of the Atlantic States, has its congeners 

 mainly in Eastern Asia. The solitary North American Pilea is confined 

 to the Atlantic States, and the same of BoeJwieria. 



