39 



shows that they are manifestily variably localized forms of recent 

 'origin and with no Mexican connection. Take for example the species 

 of the Navajo Basin. The exclusive species are A. Coltoni and its 

 forms (though this occurs sporadically even afe far as Pioche), de- 

 tritalis, Duchesnensis, Kaibensis, Episcopus, forms of junceus and 

 moutanus, sesquiflorus, Wingatensis. The Inflati have lutosus, puben- 

 lissimus, Wetherilli, while subcinereus, Waidi and metacarpus are 

 ;iearly local, and only Geyeri, lentiginos is, pictus, oojjhorus and 

 s-abulonum are at all widely distributed. Of the Preussii ampullarius, 

 r 3C epif doides, Pat*-v.-soni sabulosus and Preu3;>ii are most local 

 and only Pattersor.i passes its borders a little, and Preussii only 

 has any considerable distribution in the the Great Basin. A. Mortoni 

 is generally distributed, A. Brandegei and straturensis are local. 

 These are not of the Preussii. Of the Argaphylli A. cymboides, des- 

 peratiis and Musiniensis are local, pygmasus nearly go extends to the 

 Mogollons, while Utahensis and Purshii cover the region to the 

 Sierras. Of the Mollissimi A. Bigelovii alone extends through to 

 eastern Nevada and southward. Of the Ocreati every species is local 

 except confertiflorus which runs up into the Green River Basin. Of 

 the Bisulcati A. Osterhouti only is local, and Haydenianus extends 

 only to central Nevada. Of the Lonchocarpi the single type species 

 extends only to central Nevada. Of the Hamosi A. ('alycosus extends 

 throughout the Great Plateau. Out of the forty seven species twenty 

 six are local and half the rest are only slightly extra-limital, and only 

 two or three go to the Arizona deserts. 



Of the Green River Basin (to the north of the Uintas) there is one 

 exclusive species A. Grayi. 



The species of the Great Basin show siniillar localization. Out of 

 its thirty nine species and about twenty varieties A. serpens of the 

 Inflati is local; of the Podo-sclerocarpi Casei, pterocapus,tetrapterus. 

 Serenoi, Toanus are local; of the Inflati Beckwithii is uearly local. 

 Of other groups are forms of arrectus ati-atus, pinonis, iodantus. 

 malacus. Anderson! are exclusive or nearly so, or abuot fifteen out 

 of forty seven forms, while nearly a dozen more are only a little 

 extra-limital. 



In the Columbia Basin A. speirocarpus, sclerocarpus, inflexus and 

 succumbens are local out of fourteen species. 



In the Rio Grande region only Feensis and oocalycis are Ic^cal. 

 due to lack of barriers. 



In the Mogolion plateau region the Homalobi have A. Gilensis 

 as an exclusive; the Inflati have nutans, allochrous, Palmeri, Thur- 

 beri; the Lotiflori A. accumbens. Other groups have Cobrensis, re- 

 curvus, remulcus, Phoenicis, funereus, coccineus, ensiformis, Arizonicus. 



The Sierra Madre region has scalaris and Goldmani as exclusives. 



In the Plains region the only exclusives are lotiflorus, anisus, 

 pectinatus and parviflorus. 



The eastren region has villosus, Tennesseensis, distortus and 

 possibly glaber as exclusives. 



The Sierra region has few exclusives such as bicristatus, pachypus, 

 Bernardinus, with Andersoni and Gibbsii nearly so. The total species 

 in this life zone are 152 or 35 per cent of the whole. 



This life zone ocupying the center of the Great Plateau has barely 

 got a footing in the center of the Columbia Basin and extends but 

 little north of Pueblo Colorado. At the south it has been exterminated 

 at all elevations below 3,00o 'jt. in the Utah-Nevada region, and at 

 all elevations below 4000 ft. in the Arizona region, the Tropical takin-? 

 its place. This has resulted in broad fringes around nearly all the 

 mountain ranges at the south and limited by live oaks. 



