We used an extreme value distribution for the fit curve shown by the bold line: Frequency at any protein length x is given by, y = exp(c-b(x-a)-exp(-b(x-a)) where a = 211.0, b = 0.007142, and c = 0.2277. Note that some sequences longer than 983 amino acids are not shown in the graph. Two letter abbreviations are defined in Table 1. It is evident from the figure that at shorter protein lengths thermophiles exceed the fit curve while mesophiles are below it, but at the longer protein lengths mesophiles exceed the fit curve and thermophiles go under.