Books that have passed through the hands of Quaritch can usually be recognised by ne or more of a number of markings.
Bernard Quaritch senior's price-code was "kingalfred" (k=1, i=2, n=3, etc), so, for example, "ka/-" represents 15 shillings.
Around the turn of the 20th century a new price-code was adopted, using a series of symbols such as an "X", a shape like a letter "L" rotated 90, 180, 270 and 360 degrees, a triangle and upside-down triangle, angle-brackets "]" and "[", and "0". Usually these symbols are found in the upper right corner of the back pastedown, and a stock/inventory number in normal arabic numerals are towards the bottom left corner.
Examples of Quaritch catalogue entries may be found here