Adult C. volcani are medium-sized (TL to 320mm) caecilians with 112-124 primary annular folds and 14-37 secondary annular folds. The eyes are visible under the skin, splenial teeth are present, the tongue has dark narial plugs, and the total length divided by the mid-body width is 30-37. Coloration in life is a uniform slate gray, vaguely lighter on the head, neck, and lighter still on the lips and underside of the snout. In preservative the dorsum of the animal is dark charcoal grey with a lighter shade on the sides and belly. Annular folds are darker than the lateral coloration. The snout is light tan as are the margin of the lower jaws, and a small circle at the vent.
- Ahl, E. (1924). ''Über einige afrikanische Frösche.'' Zoologischer Anzeiger, 59/60, 269-273.
- Savage, J.M. and Wake, M.H. (1972). ''Geographic variation and systematics of the Middle American caecilians, genera Dermophis and Gymnophis.'' Copeia, 1972(4), 680-695.