Yes, it is. The 2nd Battalion TST Jerry refers to was part of the 14th Brigade territorial militia. That organization, based on the militia act of 1858, defined territorial brigades comprised of two or more counties, with battalions or regiments organized along county lines (some of the more populous counties would have more than one regiment), and companies along the judicial beats or precincts of a county. According to law, all male citizens between 18-45 (later 50) were required to enroll in the territorial militia or state troops. The law was revised in December 1861 and 1863, adjusting the number of brigades etc. Basically, all males of the above mentioned age who were not in the Confederate army belonged to this reserve militia organization (on paper). As the demand for troops to the Confederate army increased, many Confederate units were recruited on the basis of such militia companies, as Jerry's example shows.
In June 1863, however, General Magruder, fearing a Federal invasion of Texas, requested Governor Murrah to mobilize the militia. Murrah followed suit, and during August to October 1863, implemented the mobilization of 50% of the Texas State Troops (later increased to 75%) for 6 months active service. The way this was done was that each brigade district established an assembly camp where the men called up reported for duty and were organized into companies, battalions, and regiments according to Confederate army standards (which, among other things, prescribed a certain minimum personell strength of companies, etc.). In other words, the territorial regiments/ battalions and companies - based on counties and county precincts - were not activated as such. By that time, the Confederate army had - through concription and otherwise - already absorbed most of the available manpower, so that the old territorial militia organization was at this point only used to administer the mobilization, whereas field units - such as the 2nd Battalion, TST - had to be organized once those available for service reported for duty, the numbers of whom could vary widely from precinct to precinct and county to county.
As the original 6 month term of service of these state troop units was about to expire in early 1864, Governor Murrah extended the term for another 6 months, to keep them on active duty until the summer-fall of 1864. However, the new Confederate conscription act of February 17, 1864, made most of the men serving in these units liable for service in the Confederate army. Consequently, the mobilized Texas State Troops regiments and battalions were gradually phased out in May-June 1864, and the men assigned to strengthen or expand existing Confederate units. Murrah had originally wanted to transfer them as they were, i.e. as regiments and battalions, but Magruder refused to accept it. Instead, they were transferred either as companies or as individual soldiers.
I am unsure as to which district or counties the 2nd Battalion TST came from, however. I believe the TST units were assigned regimental and battalion numbers according to a system, but I have been unable to learn what that was.