This usually solitary species is globular to short-columnar with dark spines contrasting against the white wool and bristles. The copious wool is the inspiration for the epithet from Greek chion, snow, plus cephala, head. The flowers are white to delicate pink. The form offered here is the one known as M. ritteriana and differs in its thinner, longer spines. It is reported from rocky slopes at about 1000 m altitude between Monterrey (Nuevo León) and Saltillo (Coahuila), Mexico. HBG 123344, $6.