Research: Canon, Rounds, Catches

I knew what canon was prior to this exercise, although I had no idea of the theory behind how it works. Rounds and catches weren't familiar terms to me before, but once I had started reading the course materials in Part Three, it was clear there was an association with canon. I decided to do some research to find out the similarities and differences between the three terms.

Rounds

A simple form of canon.
The melody is comprised of a single chord, or chord progression.
Each voice begins at different times, so that different parts of the melody harmoniously combine.
Melodic decoration can be used.
Popular examples include Row, Row, Row Your Boat and Frère Jacques.

Catches

A type of round where the phrase in a single line of lyrics is not apparent until the lyrics are split between the different voices.
Tended to be humorous or bawdy, with a punning, non-musical point.
Rounds had a folk or traditional origin, of musical interest only.
Mostly for three voices.
The double entendre was the favored device in the bawdy catch.

Canon

Many types of canon, including:

Rounds - where the voices imitates exactly, at the octave or unison

Accompanied canon - has one or more independent parts that does not imitate

Strict canon - follows the exact interval quality of the leader

Free canon - follows the interval number, but not the quality (major/minor)

Inversion canon - the follower follows in contrary motion (e.g. up by the same interval instead of down)

Retrograde canon - follows the leader backwards

Sources:

http://www.hoasm.org/VIIA/CatchesGlees.html
http://en.wikipedia.org/wiki/Canon_(music)