We have photometrically monitored ( Cousins I _ { C } ) eight low mass stars and brown dwarfs which are probable members of the Pleiades .
We derived rotation periods for two of the stars – HHJ409 and CFHT-PL8 – to be 0.258 d and 0.401 d , respectively .
The masses of these stars are near 0.4 and 0.08 M _ { \odot } , respectively ; the latter is the second such object near the hydrogen-burning boundary for which a rotation period has been measured .
We also observed HHJ409 in V ; the relative amplitude in the two bands shows that the spots in that star are about 200 K cooler than the stellar effective temperature of 3560 K and have a filling factor on the order of 13 % .
With one possible exception , the remaining stars in the sample do not show photometric variations larger than the mean error of measurement .
We also examined the M9.5V disk star 2MASSJ0149 , which had previously exhibited a strong flare event , but did not detect any photometric variation .