carapace
1. The domed top of a chelonian shell (Chelonia), composed of two layers:
a. an inner body capsule of interlocking plates (the median neurals associated with the vertebrae; the lateral costals associated with the ribs, and encircled by the marginals); and

b. a covering of horny scutes, forming a similar pattern but not corresponding exactly to the underlying bones.


2. See CEPHALOTHORAX.

carapace
1. The dorsal part of the exoskeleton of some crustaceans (e.g. crabs), which spreads like a shield over several segments of the head and thorax.

2. The domed dorsal part of the shell of tortoises and turtles, formed of bony plates fused with the ribs and vertebrae and covered by a horny epidermal layer. The ventral part of the shell (plastron) is similar but flatter.

car·a·pace / ˈkarəˌpās/ • n. the hard upper shell of a turtle or crustacean.

carapace body-shell of tortoises, etc. XIX. — F. — Sp. carapacho, of unkn. orig.