Dr. Henry Schaerf has kindly pointed out the following gap in the application of Proposition 1 of [1] to the main example of a measurable predicate, st V where E is a Borel subset of a topological group G. Namely, this predicate is measurable with respect to the Borel subsets B (G x G) of G x G, but not necessarily with respect to B(G) x B(G), the smallest a-algebra containing {E x F: E, F C B(G)}. Hence Proposition 1 does not apply. (An example where B (X x X) 34 B (X) x B (X) for a topological space (though, admittedly, not for a group) is given in [2, p. 222, (17-17)].) Since this mistake is clearly easy to make (see also [4]) and yet the needed form of Fubini's theorem is difficult to find, it seems worthwhile to make a careful correction. The easiest rectifying assumption to make is that all groups in [1] satisfy the second axiom of countability. It is then easy to show that B (G x G) = B (G) x B (G) and a standard form of the Fubini-Tonelli theorem [3] applies. Another way to rectify [1] is to assume that all spaces are locally compact Hausdorff and that all measures on them are complete and regular (as well as a-finite). Here, we are using the following DEFINITION [2, p. 109]. If X is a locally compact Hausdorff space, M a a-algebra in X, and At a positive measure on M, then At is called regular if the following conditions hold: (i) M contains all open sets; (ii) AtF < xo if F is compact; (iii) if G is open, AG = sup{pF: F c G, F compact}; (iv) if A C M, AtA = inf{AtG: A c G, G open}. A complex measure At is regular if IAytI is. We call a function f on a positive measure space (X, M, At) p-summable if f is M-measurable and jx If I dy < ox. From [2, Theorems 17.12 and 17.13 on p. 215, Theorem 17.8 on p. 212, and pp. 199-200], we have the following form of