The lined snake is a small snake (length from 7 to 12 inches) that is phylogenetically related to the water snakes and garter snakes. Like the garter snakes, lined snakes typically have three longitudinal stripes, one mid-dorsal and two dorsolateral. The lined snake gets its common name from a double row of dark hemicircles on the yellow or cream-colored belly. Like the water snakes and garter snakes, lined snakes have a "musk" gland that opens into the cloaca, which produces a smelly secretion; presumably this is a predator defense mechanism (as if pooping on you wasn't enough!)

The lined snake is an inhabitant of prairies and savannas; its range includes much of central Texas, northward through central Oklahoma, central and eastern Kansas, southeastern Nebraska, southwestern Iowa, and western Missouri. There are disjunct populations in Illinois and the plains of eastern Colorado. It is nocturnal, and spends the day hiding beneath debris or rocks. It is tolerant of human activity, and is probably the most common urban snake, where it is found in lawns, parks, and other mowed areas (including college campuses). Lined snakes have been reported to eat nothing but earthworms, but I suspect they would take other soft-bodied invertebrates if given the opportunity.

Lined snakes overwinter in crevices, burrows of other animals, or deep in piles of debris. They emerge in the spring (the timing depends on the latitude); mating occurs in both the spring and the fall. Females give birth to living young, typically 2-12 per litter. The babies are about 2 inches long, and grow for two years before reaching sexual maturity. Lined snakes are sexually dimorphic in tail length (the tail is posterior to the transverse cloaca). Because the hemipenes are in the base of the tail in males, their tails are significantly longer relative to the length of the body than is the tail of females

Viviparity (giving birth to living young) and oviparity (laying eggs that develop and hatch outside the female's body) both occur in snakes. In fact, there are some species in the family Colubridae that are oviparous and others that are viviparous. The lined snake and the phylogenetically related water snakes and garter snakes are viviparous; the racers, rat snakes, green snakes, and others are oviparous. Rattlesnakes and their relatives in North America are viviparous, but the related vipers of South America are oviparous. The same pattern is seen in other families of snakes.

A similar pattern of viviparity and oviparity occurs in the lizards, where different genera in various families have different modes of reproduction. The plesiomorphic condition in the lepidosaurs (indeed in all of the amniotes) is oviparity. What does the pattern of occurrence of viviparity in lizards and snakes tell you about the evolution of this character in the lepidosaurs?