Merriam maintains that the western boundary of the Kato runs along the South Fork of the Eel and he is partly supported in this by Barrett (1908, map), whose boundary includes the drainage of South Fork but not the drainage of Hollow Tree Creek. Barrett, however, disavows any certainty on this particular boundary. Kroeber's line, which does include the drainage of Hollow Tree Creek in Kato territory, is supported by a specific statement from Gifford (1939, p. 296) that "Hollow Tree Creek did not belong to the Coast Yuki although they fished there." I have therefore accepted Kroeber's version. All authorities agree on the southern and eastern boundaries of the Kato as far north as the drainage of Blue Rock Creek. Merriam claims this drainage for the Wailaki, whereas both Kroeber and Foster claim it for the ta'no'm tribelet of the Yuki. It is evident that this territory was disputed, for it was the scene of several of the wars involving the Wailaki, the Kato, and the Yuki (Kroeber, 1925_a_, p. 165; 1925_b_). Kroeber obtained a detailed list of place names in this area from a ta'no'm Yuki, whereas Merriam's Wailaki information is only of a most general nature. For this reason I have given the territory to the Yuki. All the authorities, except Foster, agree on the rest of the southern boundary of the Athabascans. Foster has the Yuki-Wailaki line cross Hulls Creek about five miles from its mouth instead of passing south of its drainage. Both Kroeber and Merriam favor the more southern line, and Goddard (1924, p. 224) says that the Wailaki claimed a fishing spot in the disputed area, so I have accepted this version. The eastern boundary of the Athabascans runs north along the ridge separating the drainages of the North Fork and Middle Fork of the Eel until it reaches the headwaters of the Mad River. Thence it runs in a northern direction along the ridge that separates the drainage of the Mad River from that of the South Fork of the Trinity until it reaches Grouse Creek, where it turns eastward to cross the South Fork of the Trinity at the mouth of the creek. It continues north on the east side of South Fork, following the crest until it crosses the main Trinity about five miles above its confluence with South Fork, and then follows around the headwaters of Horse Linto Creek and Mill Creek. Merriam's eastern Athabascan boundary conflicts with the one drawn by Kroeber, Foster, and Goddard in assigning the northern part of the drainage of the Middle Fork of the Eel to the Pitch Wailaki instead of to the Yuki. Merriam is almost certainly wrong here, for Goddard (1924) definitely does not include this area within Wailaki territory and his information in this region appears to have been especially reliable. Moreover, Merriam got his information from natives of the main Eel River, who were evidently not on good terms with their relatives to the east and knew little about them. I have therefore accepted the Kroeber boundary.