Answer:
The allusions are: The song I Puritani, the composer Vincenzo Bellini, the author Walter Scott and the novel Old Mortality.
Explanation:
Allusion is a figure of language that promotes quotation or reference, within a text, to someone or some work. We can see several hints in the sentence shown in the question above. That's because when presenting the song "Arrayed for the Bridal", the author alluded to the opera "I Puritani" composed by Vincenzo Bellini and the novel "Old Mortality" written by Walter Scott.
In other words, the allusion is a reference to a work or to someone known to the author. This figure of speech serves primarily as a rhetorical resource that exemplifies an element and establishes a comparison with something similar.