[T]o the Earl was allowed the Crown Naval, but to the Marquis was anciently given a Crown Mural: and now, being altered with other fashions forsooth, it must rather be
a garland of flowers, that is to say, a Crown fleury, of quatrefoils.
– From The Blazon of Gentrie by Sir John Ferne (1586), p137
From The Manual of Heraldry by Anonymous, p76 Blazon: “Argent, a chevron or, between three crosslets sable, on the fess point surtout the chevron an escutcheon of pretence gules three quatrefoils argent”
Arms of Leipzig, Germany Blazon: Per pale azure a city wall with a tower or windowed sable and vert a pall reversed argent between three quatrefoils of the second pierced of the field; overall on a chief of the fourth … Continue reading →
[In addition to the label for the eldest son,] the other marks of difference are: For the second son a crescent; for the third son a mullet; for the fourth son a martlet; for the fifth son an annulet; for the sixth son a fleur-de-lis; for the seventh son a rose; for the eighth son a cross moline; for the ninth son a double quatrefoil.
A Complete Guide to Heraldry by A. C. Fox-Davies, p. 488