Generally speaking, the genetics of the largest order of insects, the Coleoptera, is poorly known. From time to time genes affecting the phenotype of beetles of various families (Coccinellidae, Chrysomelidae, Curculionidae, Bruchidae and Tenebrionidae) have been reported. In most species, however, descriptions have been restricted to one gene, with no mention of other genes. A promising beginning was made by Breitenbecher (1921, 1922, 1923, 1925, 1926) who found a score of heritable variations in Brz~chz~s (=Calosobrz~chzu) qz~adri7naculatz~s Fabr., but concentrated primarily on sex-limited characters with no attempts to establish linkage between then]. A group of European investigators studied heritable characters in Tenebrio 17zolitor L. Arendsen Hein (1920, 1924, 1924a) found three body colors, three eye colors, and a head and eye abnormality. After Arendsen Hein's death Ferwerda (1928) worked out the genetics of eye color and established that two of the characters were controlled by genes located on the same autosome. Schuurman's (1937) chief contribution was in determining that crossiilg over in Tenebrio occurs with equal frequency in the autosomes of males and females. Perhaps because Tenebrio requires a minimum of nine months to coillplete its life cycle, further work on the genetics of this beetle was abandoned. T w o other tenebrionids, Triboliz~nz castanez~m Herbst and T. co~zfz~sr~m Duval, have been the subject of intense investigation from the standpoint of population ecology. From time to time mutations have been reported for these species (a review of literature on the genetics of flour beetles in Sokoloff, 1960), but the number of genes described in the two species combined is of the order of half a dozen. As a result, few iilvestigators (Kollros, 1911; Bell and Moore, 1958; and McDonald, 1959) have used these species in population genetics problems. Previously, Sol<oloff (1960) reported recombination between the sexlinked genes paddle (pd) and miniature-appendaged (ma). The purpose of this paper is to provide information on three more mutations of presumed spontaneous origin. As they have been located on the X chromosoine also, a chromosome map bearing five points is included. Experiments are in progress to localize a sixth (sex-linked lethal) gene.