The pathogenesis of melanocytic nevi is not known, although several divergent hypotheses have been advanced. Consequently, it is not possible to date the earliest changes leading to the formation of these lesions. Hairy nevi, especially the giant bathingtrunk type, and about 2% of other nevi are present at birth. The majority usually first appear in infancy and childhood. Apparently the earliest appearance of pigmented nevi in the fetus has not been recorded. S. W. Becker Jr., in an examination of over 100 fetuses in various stages of development, has stated that he failed to find any nevi.1 Divided nevus is a term which has been applied to a special type of melanocytic nevus involving both upper and lower eyelids, the lesion being unique in that it is composed of two parts which form a continuum when the lids are closed. The divided nevus has interest beyond its value as