Type locality of Hylobates concolor leucogenys

Kloss [1929] restricted the type locality of the northern white-cheeked gibbon, Hylobates concolor leucogenys, on the basis of two specimens that were collected at Muang Khi, Laos, not at Muang Pak-Lay, Laos, as conventionally assumed. The locality difference is zoogeographically important because Muang Khi is east of the Mekong River, within the known range of H. c. leucogenys, whereas Muang Pak-Lay is west of the river, outside the known range of the subspecies. The type-locality restriction is appropriately amended.