Thompson, S. (1932-36). Motif-index of folk-literature; a classification of narrative elements in folk-tales, ballads, myths, fables, mediaeval romances, exempla, fabliaux, jest-books, and local legends (Indiana University studies ... Studies no. 96-97, 1Covers folktales worldwide.
The synopsis of the index starts on page 21 of volume 1 (p. 31 of the HathiTrust scan). The broad categories include: A. Mythological motifs, B. Animals, C. Tabu (i.e., Taboo), D. Magic, E. The Dead, F. Marvels, G. Ogres, H. Tests, J. The Wise and the Foolish, K. Deceptions, L. Reversal of Fortune, M. Ordaining the Future, N. Chance and Fate, P. Society, Q. Rewards and Punishments, R. Captives and Fugitives, S. Unnatural Cruelty, T. Sex, U. The Nature of Life, V. Religion, W., Traits of Character, X Humor, and Z. Misc. Groups and Motifs
On page 32 of this same volume (p. 41 of the HathiTrust scan) begins a bibliography and list of the matching abbreviations that are referenced in the topical entries. These are the sources you can look up in HOLLIS after you have identified tales and myths of interest.
The mythological motifs section begins on p. 53 of this same volume (p. 63 of the HathiTrust scan), including a detailed synopsis wherein the various categories of myths are organized. Entries within these categories begin on page 63 (p. 73 in the HathiTrust scan)
The motif entries continue throughout volume 1 and the next 4 volumes. Volume 6 is an alphabetical index. Each volume must be “checked out” separately in HathiTrust. While using this title in HathiTrust, take advantage of the electronic search capabilities available to you.