1. Proposition 6.3: in the genus 4 case, replace "D is a square in F_p" by (D/p) >= 0, where (D/p) is the Kronecker symbol. The hypothesis that p does not divide N and the stated exception at level 37 in characteristic 2 remain. This matters in characteristic 2: the curve X_<7>(25) has F_2-gonality 4, not 3, since its canonical quadric is nonsplit over F_2.

2. Table 2: at level 20 the subgroup should be Delta = {1,-1}, giving X_1(20); at levels 34, 43, 45, 64 it should be Delta = (Z/NZ)^*, giving X_0(N). The caption should specify nonhyperelliptic genus 3 intermediate modular curves.

3. Table 3: an incorrect conductor cutoff in the class number computation omitted 115 imaginary quadratic orders of class number at most 100. The following 21 counts # must be corrected (d: published -> correct):
   50: 75 -> 77, 52: 389 -> 390, 54: 125 -> 127, 56: 992 -> 994, 64: 1857 -> 1859,
   66: 175 -> 177, 68: 493 -> 494, 70: 127 -> 128, 72: 1963 -> 1965, 74: 104 -> 105,
   76: 506 -> 507, 78: 170 -> 172, 80: 2309 -> 2312, 82: 118 -> 119, 84: 1019 -> 1020,
   86: 106 -> 107, 88: 1413 -> 1414, 90: 238 -> 240, 96: 4289 -> 4295, 98: 132 -> 133,
   100: 842 -> 845
Every "Largest" entry is unchanged, including the bounds 253 and 652 used in the main proofs.

4. The trigonality notebook omitted 20 intermediate curves without verifying the hypotheses needed for its genus bound exclusion. These cases have now been checked and give no additional exceptions.

The geometric classifications in Theorems 1.4, 1.5 and 1.7 are unchanged.