42 BULLETIN UNITED STATES GEOLOGICAL SURVEY. \Yol.Vl. 



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

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

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

 .Mississippi Valley. Only amphigaean types occur in the Rocky Mount- 

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

 Pacific coast nourish two or 1 hire species of VacchiiumAmt no other 

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

 Northeastern Asia. 



EricixE/E. — 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 species of Arctostaphylos of the Mexican type, for its solitary 

 Lcucothoe far away from congeners, its shrubby Gaultheriaj and its spe- 

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

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

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

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

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

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

 Bejaria. Only the counterpart Asiatic region excels it in Rhododendron 

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

 of these. Menziesia in one species occurs over the breadth of the con- 

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

 Japan, w r here there are more. 



Pyroline^e (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 Pyrola and the 

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

 floras possess their full share. 



Monotrope.e. — Also are strikingly American, notwithstanding the 

 wide distribution of the typical Monotropa from South America to 

 Himalaya, and to Europe of Bypopitys. All the genera and species, 

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

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

 genera are peculiar. 



LENNO \ci;.i: — A .Mexican group of three genera, having the habit of 

 Monotropea : lias one genus, Vholisma^ od the const <>f California, and 

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

 head <>f the dull' of California. 



DlAPENSIACEiE, upon which we have elsewhere dilated, consist of the 

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

 monotypic genera in the Atlantic United states [Pyxidanthera and 

 Qalcuc)) of another (Shortia) divided between the Alleghanies (where it is 

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



