nEntoplastron(Anat) The median plate of the plastron of turtles; -- called also entosternum.
Century Dictionary and Cyclopedia
nentoplastronThe single median and anterior one of the nine pieces of which the plastron usually consists in chelonians or turtles and tortoises: so named by Huxley to avoid the use of the more frequent name entosternum, as the plastron is not now supposed to contain any sternal elements. See epiplastron, and cuts under carapace, Chelonia (second cut), and plastron.
Webster's Revised Unabridged Dictionary
Ento-, + plastron,
The posterior process or "tail" of the entoplastron extends to, or nearly to, the bony transverse hinge.
"Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz" by John M. Legler