It was conceded on the argument that, upon the record as presented, the plea of payment, if established, and not that of estop-pel, constitutes the only valid defense to plaintiff’s claim. Annotation: 25 A. L. E., 170. As this was not passed upon in the court below, and the evidence directed to- the point is nebulous, the case will be remanded for further proceedings.

Error in dismissing the action upon the plea of estoppel having been confessed, necessarily works a reversal of the present judgment. An appeal ex necessitate follows the theory of the trial. Hargett v. Lee, 206 N. C., 536, 174 S. E., 498; Walker v. Burt, 182 N. C., 325, 109 S. E., 43; Shipp v. Stage Lines, 192 N. C., 475, 135 S. E., 339.

Eeversed.