ABSTRACT
The opportunity to correct errors of detail, which this new edition provides, is a privilege for which I am exceedingly grateful. No broad revisions have been undertaken, but the small fussy shifts involved here are more trouble in the issuing of a book than one is likely to think, and the less the reader notices them the more successful they are. In planning them, I have checked a number of new publications as well as reviews of the original edition (1963), and have been glad to make use of improved information and convincing guesses. In cases where I have not used changes proposed in the same publications, it may be generally understood that I was not convinced.
