The dance name is a mild pun on pas-de-basque as the fourth step to be learnt by a Beginner. 

The devisor also suggests a 3-couple variant where couples 1,2 and 3 dance 6 hands across on bars 17-24 and 6 hands round and back on bars 25-32.

(Source: <<http://www.scottish-country-dancing-dictionary.com/dance-crib/step-forth.html|Scottish Country Dancing Dictionary>>)