Eggs collected locally and incubated. Incubator malfunction exposed eggs to higher temperatures than usual for several days, resulting in several hyomelanistic hatchlings with carapacial scute anomalies.
From Holbrook, North American Herpetology, circa 1842 (public domain). This is a modified version of a plate from this work at the Biodiversity Heritage Library. I cropped and cleaned up the image quite a bit--removing the yellow cast and enhancing contrast and color a little. More of these images are posted on Wikimedia Commons, and I will be adding more as time allows.
great meadows nwr. concord, ma. status-- listed as "threatened species" in massachusetts (as well as illinois, iowa, minnesota, new york, and wisconsin. listed as "endangered" in maine, nebraska, south dakota, missouri, and nova scotia).