March 18, 1880] 



NATURE 



47i 



Koren and Danielssen to complete the sketch of the 

 order according to our present knowledge. 



Order : Elasmopoda {l\avvu>, to move). 



Body distinctly bilateral. Ambulacra well defined. 

 The lateral 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 distinctly opposed across the ventral surface. The 

 odd ambulacrum naked or very seldom with a few rudi- 

 mental 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 distinctly 

 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 papillae. No respiratory 

 trees. Integument naked, spiculous, or plated. 



Deima, n.g., Figs. 2, 3 (tieifia, a fright). 

 Back highly convex ; ventral surface flat. Mouth 

 anterior, ventral ; anus posterior, ventral. Tentacles 

 small, perfectly retractile, about twenty (?). The lateral 

 ambulacra of the trivium with large pedicels, slightly 

 retractile at their ends alone, disposed in a single row all 

 along each side of the ventral surface, and with another 

 series of highly elongated, conical, rigid, not retractile 



FlGS. 2, 3. — Deima fastorttm, Thijl. Latiral and ventral views 



processes, placed externally and above the pedicels all 

 along each side of the body and directed straight out- 

 wards. The odd ambulacrum naked. Bivium with 

 processes, resembling those of the trivium, disposed in a 

 single row all along each of its ambulacra. Processes 

 forming transverse rows, more or less distinct. Integu- 

 ment with crowded, irregularly rounded, perforated plates. 

 D. validitm, n.sp. D.fastorum. 



Oneirophcmta, n.g., Fig. 4 (6v(ip6<pavra, a vision). 

 Back highly convex ; ventral surface flat. Mouth 



anterior, subventral ; anus posterior, ventral. Tentacles 

 twenty, large and retractile at their ends alone. The 

 lateral ambulacra of the trivium with large pedicels, 

 slightly retractile at their ends, disposed in a double 

 row all along each side of the ventral surface, and with 

 another series of highly elongated, conical, more or less 

 flexible, not retractile processes, placed externally and 

 above the pedicels all along each side of the body. The 



FiG. 4. — Onciro/hanla tinctabilh, Thee!. Ventml surface. 



odd ambulacrum, with a few more or less rudimental 

 pedicels. Bivium with processes, resembling those of the 

 trivium, disposed in a single row all along each of its 

 ambulacra. Processes not forming transverse rows or 

 very indistinct ones. Integument with crowded, irregularly 

 rounded, perforated plates, often provided with minute 

 processes. 



O. mutabilis, n.sp. 



Orphnurgus, n.g. (!>p(pvrj, darkness). 



Back convex; ventral surface almost flat. Mouth 

 anterior, terminal, subventral ; anus posterior, terminal, 

 slightly dorsal. Tentacles twenty. The lateral ambu- 

 lacra of the trivium with very large, not retractile pedicels, 

 disposed in a single row all along each side of the ventral 

 surface, and with another series of slender, very flexible, 

 for the most part apparently retractile processes, placed 

 above the pedicels all along each side of the body. The 

 odd ambulacrum naked. Bivium with a crowded series 

 of numerous processes, resembling those of the trivium, 

 apparently disposed in two rows all along each of its 

 ambulacra. Integument with spicula of various forms, 

 but destitute of wheels. 



O. aspcr, n.sp. 



Cryodora, n.g. Fig. 5 (itpwf, cold). 

 Back highly convex ; ventral surface almost flat. Moulh 

 anterior, subventral ; anus posterior, terminal, subdorsal. 

 Tentacles fifteen. The lateral ambulacra of the trivium 

 with large, slightly retractile pedicels, disposed in a single 

 row all along each side of the ventral surface. The odd 

 ambulacrum naked. Bivium with slender, flexible, not 



