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Central spines 4; flowers greenish-yellow. 
Radial spines all stout and annulated. 2. E. cylindraceus. 
Radial spines of 2 kinds; the lateral slender and flexuous, the dorsal 
and ventral slightly ribbed. 3. E. Lecontet. 
Stems numerous, often growing in mats; ovary-scales subulate; fruit densely 
woolly. 4. E. polycephalus. 
1. Ecuinocactus Emory Engelm. in Emory, Notes Mil. 
Reconnois. 157. 1848. 
Type locality: “Oct. 25, 1846.” According to Emory’s notes 
he was on the Gila River in the vicinity of San Carlos Creek on 
this date. 
Distribution: Central and western Arizona, southward into 
Sonora and Lower California, and westward into southern Cali- 
fornia. This species was reported from the “Mohave region” in 
the Botany of California, but it is not certain that Bigelow’s speci- 
mens were collected on the California side of the Colorado River. 
The species is to be expected, however, along the eastern border 
of the Mohave Desert and southward along the eastern borders 
of the State. Lower Sonoran. 
2. ECHINOCACTUS CYLINDRACEUS Engelm. Pacif. R. Rep. 4: 32. 
1856. . 
Echinocactus viridescens cylindraceus Engelm. Am. Journ. Sci. II. 
$421998. 1852. 
Type locality: “Near San Felipe, on the eastern slope of the 
California mountains.” 
Distribution: Gravelly slopes and washes along the western 
border of the Colorado Desert. Lower Sonoran. 
Specimens examined: Whitewater, Rose, 1908. 
3. Ecutnocactus Leconte Engelm. Pac. R. Rep. 4: 29. 1856. 
Echinocactus Wislizeni Lecontei Engelm. U. S. Geog. Surv. 6: 128. 
1878. 
Type locality: “First noticed by Dr. John L. LeConte, on the 
lower Gila.” : 
Distribution: Southwestern Utah, westward to the eastern 
borders of southern California, and southward through western 
Arizona to Sonora. This species was observed by Bigelow “at 
the head waters of Williams River, down this stream to the Colo- 
rado, and west of it till E. polycephalus took its place.” Coville 
