Here is the example that raised the question in my mind:
He was splashing, enjoying the jungle's great joys, when Horton the elephant heard a small noise.
Here, He refers to Horton; but one cannot see that until one reads the rest of the sentence. This contrasts with the normal placement of the nounal referent before the pronoun:
Horton the elephant was splashing, enjoying the jungle's great joys, when he heard a small noise.
Of course, now the meter isn't nearly as pleasant, so that is presumably why the former was preferred. However, it doesn't occur only in poetry. What is this form called?