American Handgunner Shooting Iron: Mexican Loop Holsters
By the mid-1870s to early 1880s Mexican Loop holsters became the fashion. They could have one, two or even three loops. The most colorful name given to one variation was the Mexican Loop with Texas Jockstrap. As the photo shows, it had a strap from the muzzle end and then spreads crosswise to hold the pouch to the back flap.
Source: americanhandgunner.com