The appellees, within the time allowed for the filing of a petition for rehearing, filed a motion for clarification of the opinion, which is in substance a petition for rehearing.' It is contended that the court was in error in modifying- the chancellor’s decree and that the decree should have been affirmed.
This contention is well taken. The modification was based upon a finding that part of Beaver Dam Island had formed within the appellants’ original boundaries and, therefore, belonged to them by operation of Ark. Stat. Ann. § 10-202 (Repl. 1956). That theory of the case was not argued by the appellants as a basis for reversing the chancellor’s decree. The statute was mentioned only in connection with the appellants’ request that if the decree should 'be affirmed the cause should, nevertheless, be remanded for a determination of what changes, if any, in the channel of the river might have been made by the Corps of Engineers after the trial of this case. It is a familiar rule of practice that an appellant waives any contention not argued in his brief. Johnson v. Gammill, 231 Ark. 1, 328 S. W. 2d 127 (1959); Bowling v. Stough, 101 Ark. 398, 142 S.W. 512 (1911). Although chancery cases are tried de novo, we do not reverse the decree upon a ground not argued by the appellant.
The decree is affirmed, without prejudice to the assertion by either party of any new cause of action that may have arisen since the trial as a result of the activities of the Corps of Engineers.