89d and 96d) may have large quantities of gas, given their late morphological types. In fact, for HCG 96d, for which a study of HI has been made by Verdes Montenegro et al. (1997), the HI gas contributes with half of the total mass. HCG 89d and HCG 96d have masses (obtained from their maximum velocities inside R$_{25}$ and the virial theorem) well below 10$^{10}$ solar masses and their colours are quite blue (B–R=0.8 and 0.97 respectively, Hickson 1993 and Verdes-Montenegro et al. 1997). It is therefore quite probable that HCG 89d and HCG 96d are “above” the T-F relation mainly due to brightening caused by star formation.

HCG 96c, which may deviate from the T-F relation for similar reasons, is the least massive galaxy in an M51-like pair (with the Seyfert galaxy HCG 96a). HCG 96c is noted by Laurikainen and Moles (1988) as the galaxy with the highest star-formation rate per unit area among interacting galaxies. Its colours (B-V)=0.95 and (U-B)=0.38 are consistent with this scenario (Laurikainen and Moles 1988).

Another galaxy that lies “above” the T-F relation is HCG 91c, which has a colour of B–R=1.08 (Hickson 1993) and a mass inside R$_{25}$ of 2.5 $\times$ 10$^{10}$ 