Her name was taken from the Substantia Nigra, the part of the brain which is black (Latin for "black substance") and it is responsible for dopamine production. Degeneration of the pimgmented neurons in this region is the principle pathology that underlies Parkinson's Disease (thank you for the smart sounding language, Wikipedia).
This is where Steph got the name for our Sheltie. It's the biology minor in her blood. Nigra, a tri-colored, had a lot of black when she was a pup, but as she grew up to be the largest Sheltie in the land (but she's not fat, mind you, she really is a mini-Colllie) the black dissipated a bit. We often refer to her as "The" Nigra -- a beast in nature that is mostly human, with a few Sheltie touches, that works on saving the world in our backyard.
When it is sunny out, we ask her if it is a "beautiful Nigra day." When she's away from home and she begins to whine at us, we ask her if she wants to go back to "Nigra's house." She dispises the mailman, one true touch of dog in her, and she likes to use her teeth to herd the other two dogs around the house.
She can speak in different languages, rolling her R's quite efficiently, and can wink at you. She pours out her soul through her eyes. They can be flirty or very annoyed, and she will let you know, especially if she has to roll those R's. And for special celebrations, she gets to wear ribbons.