Party Games
Reptile Egg Hunt
Buy plastic eggs from party supply or craft stores. Fill the eggs with goodies and hide all over your house and yard before the party.
Reptile Scavenger Hunt
Buy small reptile toys from party supply stores. (They typically sell dozens together in a tub, bag or tube. Then simply hide them all over the yard and house.
For older children, you can design a true scavenger hunt. Split the children into teams and give each team a clue to the first hiding spot. When they find the location, they will recieve a prize and a clue to the next location!
Leapin' Frog Flip
You need green fun foam and a stuffed toy frog. Cut foam into lilly pads. 
Put a point on each lilly pad (5 pts, 10 pts, 20 pts, 25 pts and 50 pts). Spread the lilly pads out with the highest points furthest away. Each child gets a turn tossing the frog onto the lilly pads. This is harder than it looks as the frog will bounce off the lilly pads. To get the points, the frog must stay on the pad.
Pin the Tongue on the Lizard
Draw a big lizard on a posterboard. Have the birthday child color it before the party. Cut out lizard tongues from pink construction paper and write the name of each party guest on a tongue. Instead of using a pin, loop a peice of tape and stick to the back of each tongue.
Don't Touch that Snake
Just like Hot Potato, except with a stuffed snake.
Mouse, Mouse, Snake!
Just like Duck, duck, goose. Children sit in a circle. One child is "it" and walks around the outside of the circle. "It" taps each child on the head and says "mouse..." At any time, the child may tap and call out "snake." The "snake jumps up and chases "It" around the circle. "Snake" must try to tag "It" before "It" sits in "Snake's" empty place.
Reptile Telephone
Children sit in a circle. An adult whispers a reptile fact into one child's ear. That child whispers what he heard to the next child, and so on around the whole circle. The last child says outloud what he heard.
Catching Reptiles
You will need a long stick, a paperclip, string, ribbon, and reptile toys. Wrap each reptile toy with a ribbon and make the bows big. Make a fishing pole with the string, stick, and paperclip bent like a hook. Everyone takes turns "catching" reptiles.
Do the Anaconda
Everyone forms a line with their hands on the hips of the person in front of them. Everyone sings "Do the Ananconda" and dances forward. On the first "Conda," everyone stops and puts their right foot out. On the next "Conda" everyone puts their left foot out and so on.