Depending on what kinds of laws you want information on, the place to start may be the website for Texas Parks & Wildlife Dept. Look for the lists of endangered herps in Texas as well as the nongame regulations.
There are a number of endangered/threatened species that cannot be caught or "harrassed" (too bad that does not apply to being run over or shot). There is a separate list of nongame species whose possession in certain numbers requires a nongame permit. And finally, Texas requires anyone "hunting" (including searching for herps) to possess a hunting license.
Laws regarding keeping herps generally are specific to the community in which you are living. Some communities outlaw certain species or require some sort of permit.
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Michael Smith
Conservation Director
DFW Herpetological Society
www.dfwherp.org