Females of _muticus_ are sexually mature when the plastron is 14.0 to 16.0 centimeters long, which corresponds to a carapace 19.6 to 22.4 centimeters (about 7-3/4 to 8-3/4 inches) long (average CL/PL approximately 1.4, see Fig. 13). The smaller adult females probably mature sexually in their sixth year, but most probably do so when seven years old. Accordingly, some _T. spinifer emoryi_, which are sexually mature at a plastral length of 16.0 centimeters, are also sexually mature in their seventh year, whereas most _spinifer_ (sexually mature at a plastral length of 18.0 to 20.0 cm., corresponding to a length of carapace of 25.2 to 28.0 cm. or about 10 to 11 inches) probably become sexually mature in their ninth year, and some when eight years old. Most males of _spinifer_ are sexually mature when the plastron is 9.0 to 10.0 centimeters long (length of carapace 12.6 to 14.0 cm. or 5 to 5-1/2 inches), whereas males of _muticus_ and some _T. spinifer emoryi_ are sexually mature at a plastral length of 8.0 to 9.0 centimeters (length of carapace 11.2 to 12.6 cm. or 4-1/2 to 5 inches). The smaller adult males are probably sexually mature in their fourth growing season. Breckenridge (_op. cit._:7, Tab. II) commented on the abundance of females between five and 12 inches in length, and males that ranged in length from five to seven inches. The abundance of turtles in these size ranges is probably due, in part, to a slowing of the rate of growth indicating the approach of sexual maturity; the abundance of the smallest males is especially in accord with the size at sexual maturity of males (about five inches). The largest acceptable record of size of _spinifer_ is 18 inches in length of carapace (Breckenridge, 1957:232). Stockwell (1878:402), however, wrote that females of _spinifer_ attain "an extreme length of from twenty-four to twenty-eight, and, in rare instances, thirty inches, with an average length of carapace of fifteen to eighteen," and True (1893:152) mentioned lengths of two feet or even more. Turtles 17 to 18 inches long are doubtless rare and probably about 60 years old. A specimen of _ferox_ lived the longest time in captivity--25 years (Pope, 1949:304). Individuals of _ferox_ probably exceed the maximum recorded length of carapace of 18-1/2 inches (Agassiz, 1857:401). The head of a _ferox_ having a width of 3-1/2 inches (Wright and Funkhouser, 1915:120) corresponds to a length of carapace of approximately 22-1/2 inches (PL/HW == 4.9; CL/PL == 1.3). De Sola and Abrams (1933:12) wrote that _ferox_ in the Okefinokee Swamp, Georgia, attains a length of two feet. The largest female of _muticus_ of which I have record is 21.5 centimeters in plastral length (KU 2308), a measurement corresponding to a carapace about 13 inches long. Mortality