Prompted by Pope Francis' pruning of the Monsignori, Fr Christopher Smith at the Chant Café links to a series of articles from the 90s on the history of the rank by Duane L. C. M. Galles. They were published in Sacred Music, the journal of the Church Music Association of America.
Fall 1995 (pp. 16-21) Part I [pdf]; Winter 1995 (pp.27-35) Part II [pdf]; Spring 1996 (pp. 13-17) Part III [pdf].
Alas there are no pictures to explain the different forms of dress.
Galles concludes:
It remains to be seen if bishops will exercise their faculty to erect collegiate churches and create canons (and canonesses) to encourage the cultivation and preservation of the solemn liturgy and the treasury of sacred music. These have now languished for three decades in the American Catholic Church, but with encouragement they may once again be cultivated, preserved and honored in a manner hallowed — as we have seen — by the most venerable traditions of the local Church.
Fr. Smith remarks:
If the present desire for decentralization is real, then what is to prevent diocesan ordinaries from establishing their own forms of clerical honorifics? What would prevent them from breathing life into an often defunct, but ancient, tradition of collegiate chapters of canons, which would lead an exemplary liturgical and common life, and also bring back some of the color and diversity of the Roman Church?