Order: ELASMOPODA '). 
Body distinctly bilateral. Ambulacra well defined. The la- 
teral ambulacra of the trivium bearing large, slightly retractile 
pedicels, disposed either in a single row, or sometimes in two 
rows, along each side of the ventral surface, and sometimes with 
another series of larger highly elongated not retractile processes 
placed externally and above the pedicels; pedicels of the two 
lateral ambulacra symmetrically arranged, being more or less di- 
stinetly opposed across the ventral surface. The odd ambulacrum 
naked or very seldom with a few rudimental pedicels. Bivium 
provided with very long not retractile processes, often disposed in 
one or more rows along each of its ambulacra and more or less 
distinetly opposed across the dorsal surface, or with only a few 
rudimental ones in its anterior part, or with a single very large 
one, resembling a broad, branched or unbranched lobe, and near 
to it some small papille. No respiratory trees. Integument na- 
ked, spiculous, or plated. 
Deima ?) gen. nov. 
Back highly convex; ventral surface flat. Mouth anterior, 
ventral; anus posterior, ventral. 'Tentacles small, perfectly re- 
tractile, about twenty(?). The lateral ambulacra of the trivium 
with large pedicels, slightly retractile at their ends alone, dis- 
posed in a single row all along each side of the ventral surface, 
and with another series of highly elongated, conical, rigid, not 
retractile processes, placed externally and above the pedicels all 
along each side of the body and directed straight outwards. The 
odd ambulacrum naked. Bivium with processes, resembling those 
of the trivium, disposed in a single row all along each of its 
1) elavvm, to move. 
2) detuc, a fright. 
