1) PERSONIFICATION (speaking about non-human entities as if they were human):
a) "In the big city the twin spirits Romance and Adventure are always abroad seeking worthy wooers. As we roam the streets they slyly peep at us and challenge us in twenty different guises."
"Romance" and "Adventure" are not people who can actually "roam the streets" and "peep at us" and "challenge us."
2) ALLITERATION (the repetition of consonant sounds at the beginnings of words, or in accented syllables):
a) Usually he passed the dispenser of the dentist's cards without reducing his store; but tonight the African slipped one into his hand so deftly that he retained it there smiling a little at the successful feat.
3) SIMILE (a comparison that uses the word "like," "as," "similar to," or other words of comparison):
a) Every half minute he chanted a harsh, unintelligible phrase akin to the jabber of car conductors and grand opera.
The word "akin" means "like," or "similar". The author is comparing the man's speach to the "jabber of car conductors and grand opera"; in other words, it is unintelligible.
4) OXYMORON (The use of contradictory terms side by side):
a) She began to eat with a sort of dainty ferocity...
"Dainty" and "ferocity" are two opposites, yet the author has combined them in one phrase.
5) SYNECHDOCHE (when a part is used to represent a whole, or a whole to represent a part):
a) She began to tell him her little story. It was one of a thousand such as the city yawns at every day.
A city cannot yawn. Rather, the author means that the inhabitants of the city tend to yawn when they stories like the girl's. Thus, the individual parts (the inhabitants) are represented by the whole (the city).
This passage could also be considered personification: the author speaks of the city as if it were a person who can yawn.