The main purpose of this study is to search for an explanation of the curious differentiation within the genus Chamaeleo. Since the species of this genus are rather doubtful units, I have studied the geograpical distribution of characters, not of the species, a method first used in botany (BAUR, ROTHMALER a.o.). I found that the number of characters is largest in east Afrika, gradually decreasing from this area to the periphery of the total range of the genus. East Africa proved to be still more important, as practically all the characters occur in it. This means that the chameleons in the other areas practically never possess characters that are not found in east Africa. This pattern of distribution fits in rather well with REINIG’S elimination theory (1938): „.. bei Einzelwanderungen wird nur ein Teil des gesamten Allelbestandes einer Art mitgeführt... eine durch Einzelwanderung entstandene Population weist eine geringere Zahl von Allelen auf als die Ausgangspopulation.” The existence of many parallel series of variation (meaning that several characters originated several times independently in different groups) led me to the conclusion that the mechanism described in REINIG’S theory as elimination, has consequences also for the genes predisposed to change into others. This reasoning gave a key to the reconstruction of the ancestral chameleon. By two different ways I arrived at the same conclusion, viz. the ancestral chameleon was probably an animal resembling mostly Chamaeleo chamaeleon s.l. (§ 21). As for this theoretical part of my study a survey of the species was needed, I first made an attempt at a natural system. I have divided the genus into groups of related species. For practical reasons the chameleons of Madagascar are treated separately. Their connections with the species of the African continent are examined in a special section (§ 11). As a result of my investigations I had to propose the following taxonomic changes: Ch. rhinoceratus var. lineatus + Ch. labordi + Ch. voeltzkowi + Ch. barbouri = Ch. rhinoceratus (§ 3), Ch. lambertoni = Ch. lateralis (§ 4), Ch. semicristatus = ♀ Ch. verrucosus (§ 5), Ch. guibei nov. spec. (§ 6), Ch. calcarifer = Ch. chamaeleon calcarifer, Ch. zeylanicus = Ch. chamaeleon zeylanicus, Ch. etiennei = Ch. gracilis etiennei (§ 12), Ch. anchietae vinkei + Ch. anchietae mertensi + Ch. marunguensis = Ch. anchietae (§ 13), Ch. unicornis = Ch. oweni unicornis (§ 14), Ch. pumilus = Ch. pumilus pumilus, Ch. melanocephalus = Ch. pumilus melanocephalus, Ch. gutturalis = Ch. pumilus gutturalis, Ch. ventralis = Ch. pumilus ventralis, Ch. ventralis occidentalis = Ch. pumilus occidentalis, Ch. ventralis karrooicus = Ch. pumilus karrooicus, Ch. damaranus = Ch. pumilus damaranus, Ch. caffer = Ch. pumilus caffer, Ch. taeniobronchus = Ch. pumilus taeniobronchus. (§ 16).