Thesquare latticeis the set of all points of the plane whose Cartesian coordinates are integers. Acellof the square lattice is a point-set consisting of the boundary and interior points of a unit square having its vertices at lattice points. Ann-ominois a union ofncells which is connected and has no finite cut set.The set of alln-ominoes,Rnis an infinite set for eachn; however, we are interested in the elements of two finite sets of equivalence classes,SnandTn, which are defined on the elements ofRnas follows: Two elements ofRnbelong to the same equivalence class (i) inSn, or (ii) inTn, if one can be transformed into the other by (i) a translation or (ii) by a translation, rotation, and reflection of the plane.