Erratum.

In the report " Variable occurrence of the nrdB intron in the T-even phages suggests intron mobility" by J. Pedersen-Lane and M. Belfort (10 July, p.182), two sentences were incorrectly printed. On page 182, the sentence beginning at the bottom of the second column should have read, "The td intron is indeed homologous throughout the T-even phages, as demonstrated by hybridization and dideoxy primer-extension analysis of pre-messenger RNA (pre-mRNA) and splice site products (11)." On page 183, in the legend to figure 2, the next-to-last sentence should have read, "Oligonucleotide probes (1 to 4) indicated by arrows are as described (21)."