Fig. 8.

EMGs from the epaxial muscles of a boa constrictor (Boa constrictor, approximate L = 132 cm) using arboreal concertina with alternating loops to climb a smooth cylinder (diameter = 5 cm) inclined 45°. The major bilateral activity of the IC without attendant activity of the either the SSP or LD (25–30 s) occurred when this portion of the body was perpendicular to the long axis of the cylinder and forming a static grip via ventral flexion. Such bilateral activity has not been observed for concertina in horizontal tunnels with flat floors and flat sides. The boxes above the EMGs are rough estimates of the time course of kinematic events. For ventral flexion of the vertebrae, ++, +, 0, and - indicate conspicuous ventral flexion, slight ventral flexion, little discernable flexion, and slight dorsal flexion, respectively. These data are unpublished observations from Jayne and Newman.