The final stanza is a continuation of an extended figurative comparison that begins a couple of lines before the final stanza. The full comparison states:
And he unrolled his feathers,
And rowed him softer Home -
Than Oars divide the Ocean,
Too silver for a seam,
Or Butterflies, off Banks of Noon,
Leap, plashless as they swim.
Throughout the poem, the speaker is observing a bird on the sidewalk. For much of the poem, the speaker's tone indicates that she admires the bird, and this comparison at the end further supports that. The way the bird moves is described as graceful. The movements are smoother "Than Oars divide the Ocean." Further, the comparison of the bird to the butterflies in the final two lines describes the movements as "plashless." According to the "Emily Dickinson
Lexicon," this word means "smoothly," "fluidly," or "gracefully." So in the last six lines of poem 359, Dickinson compares the bird to an inanimate object (oars) and another creature that flies (butterflies) to emphasize the grace and elegance with which the bird moves. This serves as a bit of a contrast to the poem's opening stanza, where the bird is described as more animalistic: "He bit an Angle Worm in halves /And ate the fellow, raw," (3-4). Over the course of the poem, the speaker's admiration of the bird's movements and mannerisms grows, and her final stanza is the one that most clearly shows her respect for this bird.