The genus _Echinocactus_ is thought to have originated on the great arid plateaus of Mexico and to have extended northward to the southwestern borders of the United States, where as many as forty species are known to grow. The group is a large one, including as many as one hundred forty species in the two countries where they are most abundant. There are no varieties in Central America, but a number in the driest parts of South America, thriving always in the gravelly or stony soils along the foothills and _bajadas_ and out on the broad desert mesas. The plants are globular or cylindric and strongly ribbed with sharp stout thorns, suggesting at once a barrel in size and shape, with its numerous nails protruding from the circular staves. They grow singly or in groups of two to four or more, from a foot to three or four feet in height, sometimes reaching nine feet. The central spines are the strongest and stoutest, usually one or more hooked, the radial spines also stout; the radial bristles or threads if present are at times rather firm and sometimes quite weak in texture. The _Echinocacti_ have no spines on the ovaries or fruit—a characteristic which differentiates them from the _Echinocereus_ Cactus. In this great field of Bisnaga, the Barrel Cacti, or Visnagita, the little fellows, we have selected about fifteen typical species although there are many other varieties. It is early in the morning of a hot June day in southeastern Arizona that we start on our sixth and last trek across the desert, armed with notebooks and other paraphernalia of the student or tourist, having selected our locale late the preceding day. Interlacing Spine Cactus (_Echinocactus intertextus_) _Southeastern Arizona, Southwestern Texas, and Northern Mexico_