Self-diffusion coefficients were obtained by means of NMR diffusometry for differing ratios of n-decyl-beta-D-glucopyranoside (C(10)G(1)) and n-nonyl-beta-D-glueopyranoside (C(9)G(1)) surfactant mixtures, along dilution lines through the micellar region of the ternary C(9)G(1)/C(10)G(1)/H2O phase diagram. Networks of bicontinuous micelles have been suggested to exist throughout the micellar regions of the phase diagram. A phase separation into two coexisting liquid solutions is observed in the dilute, C(10)G(1)-rich regions of the phase diagram. The fact that the dilution curves follow scaling relations pertaining to surfactant diffusion in a network for mixtures rich in C(10)G(1) indicates that the phase separation is due to differences in the networks in different micellar regions of the phase diagram; networks remain largely intact despite dilution down to the phase separation in the C(10)G(1)-rich region, whereas networks with scissions are predicted to exist in the C(9)G(1)-rich regions of the micellar phase.