In an attempt to verify the suggestion by Harris and Burns (1979) that M-type asteroids in general have high spin rates we are currently involved in a programme of photoelectricUBV observations of M and CMEU asteroids. Recently we have thus determined rotation periods, light-curve amplitudes andUBV colour indices for the asteroids 201 Penelope and 250 Bettina, both of which are situated in the (C,M,E) domain of the two-colour diagram. The resulting periods are very short (cf., IAUC 3523 and 3527). In general, we find that both the M and CMEU asteroid groups appear to be characterized by fast rotations, large amplitudes and an avoidance of membership in Hirayama families.