This is Elvira, who's gotten over being "Miss Hissy Bits" now (just need to find her the correct sized food) and is exploring this new area from the safety of my hand. She's been officially identified as a Texas Rat Snake (Elaphe obsoleta lindheimerii) and with good care can get up to 6 feet long, which is bound to give some human a case of the hissy fits. The folks at JBS Wetlands (who own snakes) say she looks fine.