Consistently up to the 1920s and commonly thereafter, editorial practice was to set the whole title-page in upper case letters. In the present listing, lower case letters are introduced, initial capitals being retained, either according to the consistent usage on other title-pages of the period, or else according to current editorial practice. From the 1940s, however, initial capitals were frequently reduced, at times to normal prose usage, especially on sub-titles, and this has been followed, despite the inconsistency with previous titles. Numbering and dates 7. Originally volumes were not numbered.
Some volumes carry two dates, the subscription or issue year, and the imprint or publication year.
On occasions these dates differ. This was presumably the work of the Honorary Secretary at the time, Clements Markham, but it is not clear how he obtained the information and not all the issue year dates he assigned to early volumes would seem to be correct, since some are later than the publication date. The listing below supplies the publication date, and if the issue date was different this is added in brackets. The annual reports and the British Museum date stamps on volumes suggest that occasionally the stated publication year may have preceded the actual year of release and distribution, but more research is required on this problem. Supplementary material 10.