Fraileas comprise a fascinating group of cacti related to the parodias of South America. Some resemble miniature ferocacti, eventually becoming taller than broad and forming rumpled-looking old specimens in a few years, a look that ferocacti achieve on a grand scale only after decades or centuries. F. mammifera is one of these with neat ribs lined with clusters of short, golden-yellow spines. Like the miniature Mexican Turbinicarpus, the plants are often self-fertile, thereby perpetuating the distinct morphology of local populations. These are recognized taxonomically as distinct species by virtue of both geographic and reproductive isolation. Fraileas differ from the turbinicarpi, however, in that their flowers are normally cleistogamous, i.e. forming mature fruits without the flowers ever opening. Only in the warm season are showy yellow flowers produced to attract pollinators, probably bees. We offer HBG 104732, a collection of F. mammifera known from about 250 m altitude, north of Dom Pedrito, Rio Grande do Sul, Brazil. $6.