This paper, apart from its intrinsic merits, has a peculiar interest to American anthropologists from its being the last official work of Mr. Stevenson, whose untimely death on July 25, 1888, was noticed in a former report. It shows his personal characteristics, being a clear and accurate statement of the facts actually observed and of the information acquired by him at first hand, without diffuseness or unnecessary theorizing. Hasjelti Dailjis, in the Navajo tongue, signifies the dance of Hasjelti, who is the chief or rather the most important and conspicuous of the gods. The word dance does not well designate the ceremonies, as they are in general more histrionic than saltatory. The whole of the ceremonial, which lasts for nine days, is familiarly called among the tribe “Yebitchai,” which means “the giant’s uncle,” this term being used to awe the youthful candidates for initiation. The ceremony witnessed by Mr. Stevenson was performed to cure a wealthy member of the tribe of an inflammation of the eyes. Twelve hundred Navajo Indians were present, chiefly as spectators, but that exhibition of their interest may partly be accounted for by the fact that they lived while on their visit at the expense of the invalid and occupied most of the time in gambling and horse racing. The very numerous active participants in the ceremonies, who might be called the mystery company, in reference to the early form of our drama, were not directly paid for their services, but acted because they were the immediate relatives of the invalid for whose benefit the performance was given. The tribesman who combined the offices of manager, theurgist, song priest, or master of ceremonies was paid exorbitantly for his professional services. The personation of the various gods and their attendants and the acted drama of their mythical adventures and displayed powers exhibit features of peculiar interest, while the details of the action day after day show all imaginable and generally incomprehensible changes and multiplication of costume and motions and postures and manipulations of feathers and meal and sticks and paint and water and sand and innumerable other stage properties in astounding complexity and seeming confusion. Yet, from what is known of isolated and fragmentary parts of the dramatized myths, it is to be inferred that every one of the strictly regulated and prescribed actions has or has had a special significance, and it is obvious that they are all maintained with strict religious scrupulosity, indeed with constant dread of fatal consequences which would result from the slightest divergence. In connection with this ritualistic form of punctilio, which is noticed in the religious practices of other peoples and lands, the established formal invocation of and prayer to the divinity may be mentioned. It clearly offers a bribe or proposes the terms of a bargain to the divinities, and has its parallel in the archaic prayers of many other languages.