If this be error and upon me proved,
I never writ, nor no man ever loved.
These lines are an example of a/an
Imperfect rhyme?
http://en.wikipedia.org/wiki/Rhyme#Types_of_rhyme
Couplet?
http://en.wikipedia.org/wiki/Couplet
A sonnet's concluding couplet?
http://www.shakespeare-online.com/sonnets/116.html
Could be several things!!