Describe symbolism in i was sitting in mcsorley's by E. E. Cummings

In Stanza Six, while contemplating his experience in McSor-ley's, the speaker's world is interrupted by the vision of a "bald greenish foetal head," around whose huge neck "a collar hung gently." This apparition could be some combination of dog and human, which symbolizes the degenerate atmosphere of the bar and the ways in which human beings lose dignity when alcohol takes over their bodies.