_C. c. mormon_: 51-1/2 (Museum of Vertebrate Zoology). _C. c. anthicus_: 70 (Conant, 1958:149). In my own study, the largest racers recorded from the Reservation and Rockefeller Tract had the following overall lengths: 59, 57-1/4, 55-1/2, 58 [M] (projected from stub tail). These sets of figures show that compared with the blue racer in Kansas, with which my own study was concerned, the black racer of the northeastern states reaches a larger size, while the racers of the Southeast and especially those of the far West and of southern Texas, are dwarfed. These size differences are almost certainly correlated with behavioral and ecological differences among the snakes involved. Adaptations to exploit certain types of prey and to utilize most efficiently certain habitats and types of cover, have led to divergent trends in different parts of the range. Habitat The racer dwells primarily in open situations, but as might be expected from its extensive geographic range, bringing it under the influence of diverse climates and habitats, its populations have diverged somewhat in adaptation to different environmental conditions. The eastern blacksnakes (subspecies _constrictor_ and _priapus_) seem to prefer woodland and forest edge. In central Louisiana, _anthicus_ occurs chiefly in an open type of woodland. The subspecies _stejnegerianus_ is found chiefly in brushland and thorn forest. The western _mormon_ is found in varied habitats, including moist streamside meadows, and chaparral. Published statements of herpetologists, based upon studies in limited areas, are briefly quoted below to show the trend of geographic change. _C. c. constrictor_: This snake "occurs chiefly in fields" (Atkinson, 1901:148; Pennsylvania); "in more or less wooded regions and along hillsides and among bushes" (Surface, 1906:167, in Pennsylvania); "abundant, especially in wooded regions" (Hibbard, 1936:28, in Kentucky); "dry and more or less open places" (Conant, 1938:52, in Ohio); "old fields and areas about buildings" (King, 1939:572, in Tennessee). _C. c. priapus_: In "drier parts of the [Okefinokee] swamp ... seems to prefer blueberries and saw palmettos" (Wright and Bishop, 1915:159 in Georgia); "common in grassy fields and in upland woods" (Allen, 1932:13, in Mississippi); "abundant along fence rows ... in dry pine-oak forest and in bottomland forest" (Trowbridge, 1937:296, in Oklahoma); "probably most abundant in open upland hammock or in old fields; limestone flatwoods" (Carr, 1950:80, in Florida); Oak and oak-hickory forest and small hill prairies in southern Illinois (Rossman, 1960:219). _C. c. paludicola_: In "all parts of the freshwater Everglades, in cabbage palm hammocks, in salt marshes, and in mangrove swamps. On Key Largo ... in mesophytic hammock" (Duellman and Schwartz, 1958:296, in southern Florida).