The trial court submitted this case to the jury on two theories of negligence: (1) lack of supervision, and (2) lack of adequate instruction. Although the court was correct in its final conclusion that the case should not have been submitted to the jury on the first ground, it erred in dismissing the complaint, since there was evidence to support the verdict *490on the second ground (see Gardner v. State of New York, 281 N. Y. 212). Accordingly, the judgment may not stand. Inasmuch as we cannot know on which ground the jury arrived at its verdict, there must be a new trial (Phillipson v. Ninno, 233 N. Y. 223, 225-226; Elenkrieg v. Siebrecht, 238 N. Y. 254, 263).

The judgments should therefore be reversed and a new trial granted, with costs to abide the event.

Loughran, Ch. J., Lewis, Conway, Desmond, Dye, Fuld and Froessel, JJ., concur.

Judgments reversed, etc.