ESCROLL or SCROLL: A long strip of parchment bearing the motto. It is for the most part placed below the arms, but sometimes, especially in Scotland, above the crest. Scrolls are occasionally found in both these positions.
MOTTO: Literally, “word” in Italian, this is a word or sentence upon a scroll, generally placed below the shield, but sometimes, especially in Scotland, above the crest. Many ancient mottoes were war-cries. But the generality of mottoes express a sentiment, hope, or determination. Mottoes are often borne by several successive generations, but may be changed at pleasure. The languages most used is Latin, French, and English; but in Scotland they are often in the old Lowland dialect, and in Wales, in the language of the principality. A few peers used Italian mottoes, and some recent ones are even in Oriental languages. However, there is no monopoly on the use of a particular motto, and the same motto may therefore be used by many different families. Numerous mottoes are listed and identified (and foreign ones translated) in C N Elvin, "A Handbook of Mottoes" (1860, revised edition 1971). Indexes of mottoes also appear in the Burke and Fairbairn.
From: "A GLOSSARY OF TERMS USED IN HERALDRY" by JAMES PARKER, FIRST PUBLISHED in 1894