Remarks on the Problematic Fossil Xenusion auerswaldae

Xenusion auerswaldae Pompeckj 1927 is refigured and redescribed. Some details which have hitherto been neglected or incorrectly interpreted are discussed. It is shown that each of its paired, hump-like protuberances was provided with a spine or papilla. This fact, as well as the relative size and apparent rigidity of the humps, disproves the earlier interpretations of these details as ventral (coxal) sacs. The specimen described by Pompeckj is a cast of the dorsal side of the fossil. Xenusion was an almost homonomously metameric animal with appendages similar to onychophoran lobopodia; the fossilized characters known hitherto permit no more exact classification than incertae sedis among the Articulata. Red-striped quartzites in the lowermost Cambrian of the Kalmarsund area in SE Sweden are the only rocks which may now be considered as the source of the drift boulders containing the two specimens of Xenusion found hitherto.