42 BULLETIN UNITED STATES GEOLOGICAL SURVEY, \YoI.n, 



continents. The five species of Gaylussacia (Huckleberries), and the 

 dozen or more eastern endemic species of Vacciniwn, as also the 

 peculiar genus CMogenes, sparingly enter even the eastern part of the 

 Mississippi Valley. Only amphigsean types occur in the Eocky Mount- 

 ains and in the alpine or alpestrine region. The moister parts of the 

 Pacific coast nourish two or three species of Vaccinium, but no other 

 forms; yet all the Atlantic types, except Gaylussacia, occur again in 

 ]!:^ortheastern Asia. 



Eeicine^. — In North America are not unequally divided between 

 the Atlantic and Pacific floras ; but the interior region has very few, 

 not one peculiar, and none except upon high mountains or of equivalent 

 northern range. The Pacific flora is remarkable for having an Arbutus 

 and ten si^ecies of Arctostaphylos of the Mexican type, for its solitary 

 Leucothoe far away from congeners, its shrubby Gaultheria, and its spe- 

 cies of BryantJms ; also for the peculiar Ledum which it shares with the 

 Northern Eocky Mountains. It has one peculiar genus, Cladothamnus. 

 The specially Atlantic Ericineous genera are Epigcea (yet with a Japan- 

 ese counterpart), Oxydendrum, Kalmia, Leiophyllum, and EUiottia, this 

 shared with Japan. This flora is particularly rich in Andromedecv of 

 eight or nine types, and here alone in the temperate zone we find a 

 Bejaria. Only the counteri^art Asiatic region excels it in Rhododendron 

 and Azalea; yet the Pacific flora has three or four fine representatives 

 of these. Menziesia in one si^ecies occurs over the breadth of the con- 

 tinent at the north, adding a second species on the way; thence to 

 Japan, where there are more. 



Pyeolikeje (including Clethra as the type of a peculiar tribe). — The 

 two species of the latter genus are characteristic in the Atlantic flora ; 

 they are not found west even of the Alleghanies, to which one of them 

 is restricted, North America is the headquarters of Fyrola and the 

 related genera, having nearly all the known species ; and the western 

 floras possess their full share. 



MoNOTROPE^. — Also are strikingly American, notwithstanding the 

 wide distribution of the typical Monotropa from South America to 

 Himalaya, and to Euro^DC of Hypopitys. All the genera and species, 

 except one in Himalaya, occur in North America, and all but the peculiar 

 Atlantic genus ScliweinUzia are in the Pacific flora, to which half the 

 genera are peculiar. 



Lknnoace^ — A Mexican group of three genera, having the habit of 

 Monotropew; has one genus, PhoUsma, on the coast of California, and 

 another very singular one, Ammobroma, Torr., beyond its borders at the 

 head of the Gulf of California. 



DiAPENSiACE^, upon which we have elsewhere dilated, consist of the 

 arctic- alpine Biapensia Lapponica and a congener in Himalaya, of two 

 monotypic genera in the Atlantic United States [Pyxidantliera and 

 Galax), of another {Slwrtia) AiviCieA between the Alleghanies (where it is 

 apparently verging to extinction) and Japan, of a related genus in the 



