Like most folks shipping reptiles, I label the outside of the box "Live Harmless Reptiles". I actually had some custom stickers made up to use, and they also say to avoid sunlight and extreme temperatures, because live animals are within.

On the top of the box, I add "More information under shipping label" to one of these stickers.

In the plastic pouch, under the label, I include a sticker or card that states "Ball Python (Python regius)" Number: 1 (for example--put however many animals are in the box).

This fulfills all of the labeling requirements for the Lacey Act. Placing the species and common name, and number on the outside of the box where it's easily visible instead of under the label would also fulfill the requirements, but I don't see the point in freaking out any ophidiophobes that might have to move the box. This way, anyone who wants to know what is in the box can open the shipping label pouch and look without disturbing the shipment (which is the intent of the law), but it's not right in their face if they don't care.