Lines of appreciation of Śakuntalā

[James Hegarty]

Dear Colleagues,

Can anyone recall the śloka that lionises the fourth act of the Śakuntalā? 

I mean the one that praises four verses in the fourth act etc. etc.

I would like to know the exact Sanskrit of the śloka and its source.

Thanks in Anticipation,

James Hegarty
Cardiff University