EXOSKELETON n.
The hardened parts of the external integument of an animal, including hair, feathers, nails, horns, scales, etc.,as well as the armor of armadillos and many reptiles, and the shells or hardened integument of numerous invertebrates; external skeleton; dermoskeleton.
EXUDATION n.
The act of exuding; sweating; a discharge of humors, moisture, juice, or gum, as through pores or incisions; also, the substance exuded. Resins, a class of proximate principles, existing in almost all plants and appearing on the external surface of many of them in the form of exudations. Am. Cyc.