I don't think the method of measure is spelled out in the regulation, but there are two basic ways to measure carapace length: SCL (straight carapace length) and over the curve, with SCL being the most frequently used. Over the curve is sometimes used for very large specimens (e.g. Aldabrans, sea turtles). Both measurements do run cranial/caudal along the dorsal axis. Use SCL and you'll be okay. Doug
:Ok, I know a turtle has to be a minimum of 4 inches to be sold in the pet trade in the US, but where do they measure this? I figure it's cranial/caudal length of the carapace, but I want to be sure. Thanks.