Adult female, River Road, Presidio Co., TX. Captive-bred. Photo © Brad Alexander.
Adult female, River Road, Presidio Co., TX. Captive-bred. Photo © Brad Alexander. 
Wild-caught adult male, Santana Mesa W of Big Hill, River Road, Presidio Co., TX. Collected by Ian Recchio. Note healed scar, probably the result of attempted predation. Photo © Brad Alexander. 
Captive-bred adult female, River Road, Presidio Co., TX.
Captive-bred adult male, River Road, Presidio Co., TX.
Big Hill, River Road, Presidio Co., TX. Photo © Michael S. Price. 
River Road nr Big Hill, Presidio Co., TX. Photo © Michael S. Price. 
River Road nr. Contrabando, Presidio Co., TX. Photo © Michael S. Price.
River Road at Panther Canyon, Presidio Co., TX. Photo © Michael S. Price.
Lajitas, Brewster Co., TX. Collected by M. Forstner. Photo © Troy D. Hibbitts.
River Road, Presidio Co., TX. Collected by T. Burkhardt, 2005. Photo © Troy D. Hibbitts. 
Subadult male, W of Big Hill, River Road, Presidio Co., TX. Collected by Troy Hibbitts, June 1992. Photo © Troy D. Hibbitts. 
Small adult male, W of Big Hill, River Road, Presidio Co., TX. Collected by Troy Hibbitts, June 1997. Photo © Troy D. Hibbitts. 
Adult female, W of Big Hill, River Road, Presidio Co., TX. Collected by Troy Hibbitts, June 1997. Photo © Troy D. Hibbitts.
Sub-adult male, W of Big Hill, River Road, Presidio Co., TX. Collected by Troy Hibbitts, June 1997. Photo © Troy D. Hibbitts.
Adult male, W of Big Hill, River Road, Presidio Co., TX. Collected by Troy Hibbitts, June 1997. Photo © Troy D. Hibbitts.
Adult female, W of Big Hill, River Road, Presidio Co., TX. Collected by Troy Hibbitts, July 1999. Photo © Troy D. Hibbitts. 
River Road, Presidio Co., TX. Collected by Devero. Photo © Troy D. Hibbitts.
River Road, Presidio Co., TX. Collected by Lance Benton. Photo © Troy D. Hibbitts.
River Road, Presidio Co., TX. Collected by Lance Benton. Photo © Troy D. Hibbitts. 
River Road, Presidio Co., TX. Collected by Lance Benton. Photo © Troy D. Hibbitts. 
River Road, Presidio Co., TX. Collected by Lance Benton. Photo © Troy D. Hibbitts.
River Road, Presidio Co., TX. Collected by Dave Long. Photo © Troy D. Hibbitts.
Lajitas, River Road, Brewster Co., TX. Collected by T. Gebhard. Photo courtesy of D. Vermilya.
Big Bend National Park, Blue Crk xing St Elena Rd., Brewster Co., TX. D. Miller, August 1969. Photo courtesy of G. T. Salmon. Although not geographically part of the “River Road” area, snakes from the western part of Big Bend National Park are most similar to snakes from the River Road area, and thus are included in the River Road gallery.
Castolon Rd, Big Bend National Park, Brewster Co., TX. Photo courtesy of G. T. Salmon. Although not geographically part of the “River Road” area, snakes from the western part of Big Bend National Park are most similar to snakes from the River Road area, and thus are included in the River Road gallery. 
Big Bend National Park, Castolon Rd, Brewster Co., TX. J. Fraser, Sept. 1991. Photo courtesy of G. T. Salmon. Although not geographically part of the “River Road” area, snakes from the western part of Big Bend National Park are most similar to snakes from the River Road area, and thus are included in the River Road gallery. 
Lajitas, Brewster Co., TX. Collected by P. Wright, June 1987. Photo courtesy of G. T. Salmon.
Peppers Hill on River Road, Brewster Co., TX. Collected by C. Lazik. Photo courtesy of G. T. Salmon. 
River Road, Brewster Co., TX. Collected and photographed by J. Fraser, May 1992. Photo courtesy of G. T. Salmon.
River Road, 2 miles W of Big Hill, Brewster Co., TX. Collected by K. Stricker and D. Salceies. Photo by Damon Salceies, courtesy of G. T. Salmon.
Panther Canyon, River Road, Presidio Co., TX. Collected by D. Vermilya. Photo by Ed Acuña.
TX: Presidio Co., Pinto Canyon, Chinati Mountains. July 2007. Photograph by Greg and Brooks Thode, courtesy of John Craft. Head shot of specimen depicted in next image. Although included as part of the River Road Gallery, Pinto Canyon lies north and west of the River Road, and is represented by very few specimens of alterna. 
TX: Presidio Co., Pinto Canyon, Chinati Mountains. July 2007. Photograph by Greg and Brooks Thode, courtesy of John Craft. Although included as part of the River Road Gallery, Pinto Canyon lies north and west of the River Road, and is represented by very few specimens of alterna. The buckskin ground color is somewhat unusual for this part of the range, but the overall pattern is otherwise typical of southern Presidio County snakes.
TX: Presidio Co., Pinto Canyon, Chinati Mountains. July 2007. Photograph by Greg and Brooks Thode, courtesy of John Craft. Although included as part of the River Road Gallery, Pinto Canyon lies north and west of the River Road, and is represented by very few specimens of alterna. This specimen and the other Pinto Canyon snake were found on the same night. This phenotype is typical of snakes occurring in southern Presidio County, a region of mostly dark volcanic rock.
Adult male, River Road nr Panther Canyon, Presidio Co., TX. Collected by C. Whitney.
Juvenile female from the Big Hill section of the River Road, Presidio Co., Texas. Collected by Tim Burkhardt and Mike Rochford, July 2014. Photo © Chad Whitney. 
Adult male alterna found in Summer 2014 at Peppers Hill, Brewster Co., Texas, by Jake Scott and Richard Bartlett. Photo © Jake Scott. 
Adult female alterna, found on FM 170 (River Road) W of Big Hill, in June 1974 by Ray Guese. He came upon a ringtail with the snake, and recovered the snake after scaring off the ringtail. The snake sustained only minor injuries and went on to produce several clutches of eggs at the Dallas Zool. Photograph © 1980 by David G. Barker. 
Adult female, River Road nr Panther Canyon, Presidio Co., TX. 
Adult male, River Road nr Panther Canyon, Presidio Co., TX.
River Road just W of Big Hill, Presidio Co., TX. Collected by Troy Hibbitts. 
Adult female, River Road W of Lajitas, Presidio Co. Observed by T. Burkhardt, June 2012. Photo © Troy D. Hibbitts.
Wild-caught subadult male, W of Panther Canyon, River Road, Presidio Co., TX. Observed by Chad Whitney.
River Road, Presidio Co., TX. Captive-bred subadult female.
Wild-caught male found by Colin Smith and Jeff Teel, July 2012, W side of Big Hill, River Road, Presidio Co., TX.
