Carpenter (1956:86) came to no conclusion as to the cause of shell pitting in _Terrapene carolina_ but suggested that a variety of factors including parasitic fungi, parasitic invertebrates, and simple shell erosion, might be responsible.
According to my own observations on turtles in the University of Kansas collections, shell pits range in size and shape from shallow, barely discernible depressions to deep borings; I suspect that shell pitting for turtles in general has many causes, some of which may be of more frequent occurrence in one species than in another.
Hunt (1957:20) presumably was referring to shell pitting by a more suitable name when he wrote of, "... necrosis ... of mycotic origin." Hunt (_loc. cit._) stated that "Of those cases which have been recently examined, the author found all were due to the invasion of Mucorales beneath the plates of the epidermal laminae. This disease is of extremely common occurrence and has been found in all members of the order but is seldom found in marine species. Mycosis more frequently occurs on the plastron than on the carapace." Hunt presented no evidence to support his statement regarding invasion of the shell by Mucorales.
Evidence that injury to the soft parts of the body is also fairly common is seen in the many _T. ornata_ with missing feet and legs. Stumps resulting from amputations are covered with tough, calloused skin and sometimes by horny tissue similar to that of the antebrachial scales. Amputees are incapacitated only slightly in normal locomotion if a functional stump remains; probably a cripple is somewhat handicapped in other functions, such as burrowing, nest digging (females), and copulation (males). Causes of amputation are discussed in the section on predators.
Fractures of the limb bones are common. A female from Stafford County, Kansas (Pl. 29, Fig. 4), showed a typical case of fracture and subsequent repair; the right fibula had been broken and the ends dislocated; a great mass of bone joined the repaired break to the middle of the tibia, giving the entire skeleton of the leg the appearance of the letter "H." The fibula, shortened by the dislocation, no longer articulated by its proximal end with the femur; the tibia probably bore the entire load in the period of repair and the transverse connection that formed between the bones later took over the function of the fibula.