_Distribution._--The discovery of a new _Gopherus_ from north-central Mexico increases to four the recognized forms of the genus and extends the known range of the genus onto the Mexican highlands, approximately 410 miles eastward from Alamos, Sonora (_G. agassizii_), approximately 100 miles westward from a point 2 mi. W of Monclova, Coahuila (_G. berlandieri_), and approximately 200 miles westward from Monterrey, Nuevo León (_G. berlandieri_). TABLE 2. Bodily Proportions in the Known Species of Gopherus. Two Specimens of G. polyphemus from Harmon, Mississippi (USNM 53166-7), Are Considered Separately Because of Their Notably Narrower Heads. The Size of Each Sample Is Given in Parentheses Above the Average; Extremes Are in Parentheses Following the Averages. ---------------------+-----------+-------------+-------------+-------- Species |Greatest |Height | Height |Diameter and |width of |of | of |of General Locality |skull as a |shell as a | shell as a |hind foot |percentage |percentage | percentage |as a |of |of width | of length |percentage |condy- |of | of |of width |lobasilar |carapace | carapace |of head |length | | | ---------------------+-----------+-----------+------------+---------- _G. polyphemus_ | (6) |(13) |(13) | (Florida) |.94 |.53 |.39 | |(.92-.97) |(.48-.58) |(.36-.42) | ---------------------+-----------+-----------+------------+---------- _G. polyphemus_ |(2) |(2) |(2) | (Mississippi) |.87 |.53 |.43 | |(.84-.89) |(.52-.54) |(.40-.45) | ---------------------+-----------+-----------+------------+---------- _G. berlandieri_ |(21) |(22) |(21) | (Texas and NE Mexico)|.78 |.56 |.46 | |(.70-.83) |(.48-.62) |(.43-.51) | ---------------------+-----------+-----------+------------+---------- _G. agassizii_ |(6) |(8) |(8) | (U.S. and N. Sonora) |.77 |.53 |.41 |(.38-.44) | |(.70-.83) |(.49-.58) | | ---------------------+-----------+-----------+------------+---------- _G. agassizii_ | |(4) |(4) |(4) (Alamos, Sonora) | |.56 |.39 |.92 | |(.52-.59) |(.37-.41) |(.87-1.00) ---------------------+-----------+-----------+------------+---------- _G. flavomarginatus_ |(2) |(3) |(3) |(3) (North-central | | | | Mexico) |.83 |.54 |.43 |.71