You can identify snake eggs by examining several characteristics, including shape, hardness and appearance. Most snakes lay eggs and do not give birth to live young. The female lays the eggs underground in loose soil or sand, which acts as a natural incubator. She lays them and then abandons them, unless she is a cobra or a python. Depending on the species, a female snake can lay anywhere from two eggs to one hundred in a clutch.
Lift up the egg. Reptile eggs can survive brief, gentle handling. If the shell is hard, then it's a bird egg. The shell should feel leathery and have some give to it for it to be a snake egg.
Examine the egg under a source of bright light, like a light bulb. Turn off all the other lights in the room so the one light source is even brighter. Lift the egg up to it and you should be able to just barely make out the silhouette of the embryo inside. Only take a couple minutes to do this, because the egg needs to be put back into its natural or artificial incubator.
Note the shape of the egg. Snake eggs are generally oblong, but some African and Asian snakes lay eggs that are bumpy like a ginger root or that resemble a very thick grain of rice. Most snakes native to North and South America will lay eggs shaped like bird eggs.
Contact a local game warden or wildlife sanctuary and give them a description of the eggs. They may know the species, but since snake eggs so closely resemble each other, it's nearly impossible to determine the species until they hatch.
TL;DR (Too Long; Didn't Read)
It takes about 55 to 60 days for snake eggs to hatch. Snakes that give birth to live young include garter snakes, water snakes, rattlesnakes and boa constrictors. A couple of days before the eggs will hatch, they look as if they've deflated.
If you found the eggs outside, put the eggs back, if possible. Otherwise, they will die. Eggs need to be in a few inches of dirt, peat moss or shredded newspaper in a humid room at a temperature of 80 degrees F.