Melanocytes of white (d/d) larvae of the Mexican axolotl (Ambystoma mexicanum) are confined to the dorsal midline of the trunk region, whereas in dark (D/-) larvae they are spread laterally on the flank as well, where they contribute to the normal pigment pattern of the trunk. Pigment cell migration in the subepidermal space of white larvae is inhibited by the white epidermis (Dalton '50; Keller et al., '82). The present scanning electron microscopic study describes a well-defined sequence of changes in shape and arrangement of neural crest cells during and after their segregation from the neural tube in both dark and white axolotls. The morphology of the neural crest cells migrating in the subepidermal pathway of dark larvae is correlated with their motile behavior and pattern of migration in vivo, as described by time-lapse cinemicrography (Keller and Spieth, '83). Also, the structures of the matrix material in the subepidermal space of dark and white axolotls differ in ways that may be related to the epidermal inhibition of migration in the latter. Numerous possibilities for contact guidance offered by the structure and topography of the substrata, neighboring cells, and the extracellular matrix in the migration path are described and discussed.