After I posted the other entries on Maria Martin, I realized that I neglected to refer to this outstanding series of pages from the Charleston County Public Library via the Charleston Museum.
The surviving works by Maria Martin are to be found under arranged under the headings:
Sketchbook Paintings: Gallery 1, Gallery 2.
Sketchbook Paintings: Unidentified Insects
Birds of America Paintings
These are well worth the time spent in viewing them. Below is one of the paintings from Audubon that that was in part painted by Maria Martin. Fittingly, it is of Bachman's Warbler, named by Audubon for her husband or perhaps for her as well.