What is the comparative form of dryly?

The word "dryly" is already in its adverbial form. Therefore, it doesn't have a comparative form.

To express a higher degree of dryness, you'd need to use other adverbs or phrases, such as:

* More dryly

* Very dryly

* Extremely dryly

* Particularly dryly

* With even more dryness

For example:

* "He spoke dryly about the situation."

* "He spoke more dryly than usual about the situation."