title: Erratum.
abstract: In the report "Sequence of 16S ribosomal from Halobacterium volcanii, an archaebacterium" by R. Gupta et al. (12 August, p. 656), the last sentence of the abstract should read: "Since the H. volcanii sequence is closer to both the eubacterial and eukaryotic sequences than these two are to one another, it follows that the archaebacterial sequence is more like the common ancestral sequence than at least one of the other two versions." Also, the sentence beginning on line 6, column 3, page 658, should read: "Although the root of this tree cannot be determined, the data demand that the archaebacterial version be closer to the ancestral version common to all than are one or both of the other two versions."