Abstract: As the prototype of various literary genres,oral literature can be continuously abstracted to psychological structures,and some stylistic formulas can be constructed to promote interdisciplinary dialogue.Taking folk legends as an example,proper names and their density,discrete plots,and closure/anti-closure structures of cardinal sequences serve as morphological identifiers of folk legends,which can outline the stylistic contours of folk legends as a literary genre,namely stylistic formulas.Firstly,the cardinal sequence of folk legends commonly has two kinds of structures:closure and anti-closure,which respectively point to happy endings and tragic conclusions.Secondly,proper names and generic names form a dynamic system that matches each other,and their density differences create different styles of oral literature.Thirdly,the discrete plots of folk legends have specific narrative and psychological functions,which can change the audience's psychological expectations of the genre and transform a fictive folktale into a tangible legend.The three stylistic identifiers of folk legends are not fixed.They can be intensified or weakened,meanwhile the stylistic sense of folk legend also undergoes subtle changes.Due to the fluidity of oral literature,morphological identifiers can be extracted and regarded as variables to assess the stylistic sense.The morphological methodology of oral literature research can lead to an open and dynamic stylistic view and build a bridge for interdisciplinary dialogue.

Key words: cardinal sequences, proper names, the density of proper names, discrete plots, stylistic changes