A pluteus was a machine used by infantry for protection in the field: and hence the word is applied to any fence, or boarding to form the limit or edge of anything, as a table or a bed.
"The Care of Books"
John Willis Clark
Driesch has found that a tropism underlies the arrangement of the skeleton in the pluteus larvae of the sea-urchin.
"Darwin and Modern Science"
A.C. Seward and Others