This genus includes 3 species, and of these there are a number of varieties. The plants are globular or elongated. The central spines are long, and at least one of them is sharply hooked at the tip.
Hamatocactus Setispinus. Texas and N. Mexico. This strongly armedattains a height of about 6 inches. Ribs number 13, radial spines 12 to 15, centrals 1 to 3. The flower is funnel-shaped, about 3 inches in length, whitish-yellow with a red centre.