Parallelism
Parallelism is the repetition of the same grammatical or syntactical structure in a poem. The repeated structures are often used to contribute to the rhythm of the lines and to emphasize their meaning. Parallelism tends to contribute a sense of insistence to an expression.

The description of Narcissus here takes on the conventional form of a "catalogue" in which each feature is listed in parallel phrases: "his eyes. . ."; "his hair. . ."; "his face. . ."; "his ivory neck. . ."; "his cheeks. . . ." We as readers see what Narcissus is seeing, taking an inventory of his beauty.