About 50 japygids, belonging to 29 distinct forms of which 23 are recognizable, have been collected since 1874 in caves all over the world. A list is given, by continent and by countries. Ten species found both in the soil and in caves are called troglophiles to emphasize the sorting which seems to occur among endogenous species. Of the remaining 13 species, all considered troglobites, only 3 show morphological peculiarities which can be ascribed to adaptation to cavernicolous life: (1) Metajapyx moroderi ssp. patrizianus Pagés from Sardinia shows a slightly longer 10th urite and cerci than the f. typ.; (2) Kohjapyx lindbergi Pagés from Afghanistan is characterized by its very long 10th urite, its relatively slender cerci, and the presence of more than 8 placoid sensillae (maximum basic number in endogenous species) on the apical segment of the antennae; (3) Austrjapyx leleupi Pagés from the Lower Congo fits most closely the picture of the true troglobite - almost entirely depigmented, slender, with elongate legs, long setae, and the antennae with two of the trichobothria 4 to 5 times as long as the other typical 11, as well as 14 placoid sensillae on the apical segment. It is noted in the conclusion that, among the Diplura and Myriapoda, the almost exclusively phytophagous or saprophagous Campodeids and millipedes include a large number of true troglobites, in contrast with the carnivorous Japygids and centipedes, which have very few troglobites.