The Lacey Act states:
"Except as otherwise provided in this subpart, no person may import, export, or transport in interstate commerce any container or package containing any fish or wildlife (including shellfish and fishery products) unless he/she marks each container or package conspicuously on the outside with both the name and address of the shipper and consignee. An accurate and legible list of its contents by species scientific name and the number of each species and whether or not the listed species are venomous must accompany the entire shipment."
So basically
1 Name/Address of shipper.
2 Name/Address of receiver.
3 Species scientific name.
4 Quantity per species.
5 Whether species is venomous/nonvenomous.
It is also illegal to label packages with FRAGILE/PERISHABLE only. This is viewed as an intentional and deliberate avoidance of the above requirements.
My labels read:
Live Harmless Reptile
Scientific Name: Python Regius
Common Name: Royal “Ball” Python
Quantity: One (1)
Yes - even captive born snakes fall under the heading "wildlife" Most people don't bother with Lacey labeling - but if caught both the shipper and receiver are in violation. Fines are pretty steep from what I've heard. Lotsa people ship by carriers that don't accept snakes so they don't label - lotsa people think if you label the box carriers will be afraid to deliver and there will be hold ups and dead snakes so they don't label, some people are afraid of getting the snake stolen out of the box durring shipping if they label - so they don't.
Anyway hope this helps.
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Tosha 
"Nihil facimus sed id bene facimus"
7.33.0 Ball Python (Harry and Fluffy and gang)
1.0.0 Angolan Python (Anakin Skywalker)
0.0.1 Green Tree Python (Verdi - yeah I know but my kids love the book)
0.2.0 Feline (Pippen and Pandora)
0.0.1 Desert Tortoise (Pope John Paul aka JP )
2.2.1 Fish (1,2,3,4)
0.0.2 frogs rescued from pool skimmer