Botta's pocket gopher (Thomomys bottae) is a pocket gopher native to western North America. It is also known in some sources as valley pocket gopher, particularly in California. Both the specific and common names of this species honor Paul-Émile Botta, a naturalist and archaeologist who collected mammals in California in 1827 and 1828. Botta's pocket gopher is a medium-sized gopher, with adults reaching a length of 18 to 27 cm (7.1 to 10.6 in), including a tail of 5 to 6 cm (2.0 to 2.4 in). The overall dental formula is 1013 1013. Males are larger, with a weight of 160–250 g (5.6–8.8 oz), compared with 120–200 g (4.2–7.1 oz) in the females. Male pocket gophers are widely believed to continue growing throughout their life. However, size variation would indicate that some males are predisposed to be larger than others, and the largest male may not be the oldest. Coloration is highly variable, and has been used to help distinguish some of the many subspecies; it may also change over the course of a year as the animals molt. Both albino and melanistic individuals have also been reported. However, Botta's gopher generally lacks the black stripe down the middle of the back found in the closely related southern pocket gopher, a feature that may be used to tell the two species apart where they live in the same area. Botta's pocket gophers are found from California east to Texas, and from Utah and southern Colorado south to Mexico. Within this geographical area, they inhabit a range of habitats, including woodlands, chaparral, scrubland, and agricultural land, being limited only by rocky terrain, barren deserts, and major rivers. They are found at elevations up to at least 4,200 metres (13,800 ft). Skeletal remains of Botta's pocket gophers, dating back 31,000 years, have been identified from Oklahoma.