Good catch, Robin! The 1931 Annin Catalog is one of the best flagmaker catalogs of the 20th Century. It is 454 pages, which is way more than any of their earlier editions. The 1907 Catalog had 318 pages. The 1914 edition was 326 pages and the 1923 edition has 311 pages.
One of my favorite parts of these catalogs are the pages of Confederate flags. The same small silk printed CSA flags occasionallly show up on eBay and other auctions as authentic Civil War period flags!!
You may also wish to consider the 1927 Dettra Catalog also on eBay. You can see it at:
1927 DETTRA FLAG BANNER CO. CATALOG NO. 22 OAKS PA. - eBay (item 280476777896 end time Mar-17-10 19:28:56 PDT)
The seller thoughtfully included pics of the Confederat flags page.