Gaskell Blog © Katherine C.
A Victorian mourning cap was distinguished by it’s black color or accents (depending on the level of mourning). The more recent the loss the plainer the design would be. The shape of the cap depended on the age of the widow but the most common was peaked at the front; a style inspired by Mary Stuart’s mourning. Fabrics were either of tulle, tarlatan, or lisse ( a fine, filmy, lightly crinkled gauze).
Source
“Victorian Mourning Customs from Colliers.” Quilt History- informational site about antique quilts and vintage textiles including article and an interactive chat group.. N.p., n.d. Web. 25 Nov. 2010. <http://www.quilthistory.com/VMC.htm>.
Gaskell Blog 
I wonder if this style of bonnet connects to a widows peak in people’s hairlines? It is so close a coincidence.
I’m sure that you’ll be pleased to hear that, after almost four years, the “Widow’s Peak” hairline is indeed named because of the likeness of so many bonnets/caps/veils that were worn during that period. 🙂
Laurel, yes it does! I’m researching about widow’s peak (which I have) and apparently, it traces its roots to the widow’s cap. Interesting!
Just some biblio to entice further research. In Ancestry and Narrative in Nineteenth-Century Literature, Gilmartin (64) claims that the widow cap was derived by Victoria from portraits of Mary Queen of Scots and thus (it is called the Mary Stuart cap) consciously designed after the sixteenth-century style. I wonder if it might have been derived (by Marie) from her mother-in-law Catherine de Medici who was known to set the agenda on styles in the Valois court. If so, what an interesting royal connection from the Valois to Victoria.