Barber, in his "British Family Names", mentions the name of SOUTH as one of the English names of French derivation. Lucian J. Fosdick in his "The French Blood in America" mentions SOUTH. I have also seen discussions that SOUTH (and other directional names) mean which side of the English country the family came from.
The coat of arms is very ancient, probably before 1300. The simplicity of the shield is further evidence of its antiquity. The English seldom used mottos. This accounts for the absence of Crest and Motto. Silver is the color of fidelity, truth and honor, while red denotes strength and bravery. The two bars were laced upon the silver for purposes of recognition.
Source: genealogical narrative of the Claggett and Irvine Families.