encope

from The Century Dictionary.

• noun A genus of irregular clypeastroid seaurchins, of the family Mellitidæ.
• noun It is notable for the massiveness of the calcareous test, and has a large lunule between the posterior ambulacra, in addition to five incisions opposite the ambulacra, as in E. emarginata. The mass of the test is greatest in E. grandis, a species of the west coast of Mexico.