In PG (3, q), q even, Cherowitzo made a detailed study of flocks of a cone with a translation oval as base; also called -flocks [4]. To a flock of a quadratic cone in PG(3, q), q even, there always corresponds a set of q#1 ovals in PG(2, q), called an oval herd. To an -flock of a cone with an arbitrary translation oval as base, there corresponds a herd of q#1 permutation polynomials. For some, but not for all, known examples of -flocks, these q#1 permutation polynomials define an oval herd. This leads to the fundamental problem of determining which -flocks correspond to an oval herd. This article studies a class of -flocks and explicitly describes which members of this class have an associated oval herd. To achieve this goal, all monomial hyperovals +(1, t, tI)"" t3F O ,6+(0, 1, 0), (0, 0, 1), with k"2G#2H, iOj, are determined.1998 Academic Press