The chilopods of Peru with descriptions of new species and some zoogeographical notes on the Peruvian chilopod fauna.

S ummary . The following species are described as new to science:—Notiphilides dissimilis, Schendylurus montivagus, Schendylurus peruanus, Nyctunguis weyrauchi, Diplethmus pulchellus, Prionothalthybius grandis, Schizoribautia peruana titicacae, Atethobius (Vulcanbius) weyrauchi, Lamyctes neotropicus. A re–description in detail is given of Schizoribautia seydi (Ribaut, 1923) from new material. New records arc given for Peru of Schizoribautia peruana Verhoeff, 1951, Lamyctes pacificus Silvestri, 1899 and Lamyctes cuzcotes Chamberlin, 1944, in some instances with short descriptions amplifying the original one. An incidental record of the synanthropic species Lamyctinus coeculus Brolemann from Venezuela is given. A revision and re‐grouping of the genera related to Notiphilides is given, together with some account of the observed variation of some of the morphological characters used for specific determination in that genus and some observations on the biology of species of the genus Notiphilides. Keporya miranda Chamberlin, 1941 is shown to be a synonym of Notiphilides maximilliani (Humb. et Sauss., 1870). In the second half of the paper a preliminary list is given of all the known species and subspecies of chilopods found in Peru, amounting to some seventy‐four forms in all. This list includes some names that are to appear in a forthcoming publication by Chamberlin on the chilopods of Chile. Discussing the zoogeographical relationships of this fauna it is suggested that the chilopods follow a well marked differentiation into three groupings following those of the marked geographical and vegetational divisions; these are ( a ) those of the desert and subdesert coastal region; ( b ) those of the montaña; ( c ) those of the sierra. It is shown that in some genera, especially those of the montaña, species replacement by altitude takes place and that this accounts for the large number of endemic forms. Three faunal elements each with a different history are shown to occur:—1 An early indigenous element, perhaps Mesozoic, which may have partly arisen in the northern hemisphere but which is quite likely to be heterogenous in make‐up, the members of which are often found distributed, either in identical forms or closely related species, over the Pacific Islands and sometimes in the continental masses of the southern hemisphere. Possible reasons for this distribution are discussed. 2 A small faunal element which is in process of some diffusion northwards using mostly, so far as the evidence we have at present indicates, the tropical rain forest. 3 A well marked post–Tertiary element. originating in the northern hemisphere and in process of extending its range southwards using, for the most part, the Central American pine–cedar forest. This element is composed mostly of lithobiomorphs with a few species of geophilomorphs.