OPHIUROIDEA OF THE BAHAMA EXPEDITION. 43 



O. nuttingii Ver., sp. nov. Arm-spines four, short. Oral 

 shield very large, ovate. Disk-scales more or less exposed, 

 bearing spinules. 



Group F. — Ofhiomitrella Ver., gen. nov. (See p. 39). 



Type O. lavipellis (Lym.) 



Disk- scales visible, bearing granules or spinules. Radial 

 shields partly naked, not large, wide apart. Arm-spines 

 slender, thorny or serrulate; the rows approximate dorsally in 

 the type. One tooth-papilla. In the type-species a pair of 

 special, distal, oral tentacle-papillee, on the first under arm- 

 plate, * directed into the mouth-slit. Adoral shields wide. 

 Otherwise the mouth-parts are nearly as in typical Ofhiacantha. 



O. IcevipeUis (Lym. '83). Arm-spines eight, slender, 

 thorny. Disk-scales naked or partly granulated. Upper arm- 

 plates separated. 



Group G. — Ofth/acanthella, gen. nov. Type, O. troscheli 

 (Lym.) 



Radial shields naked, long, parallel, united by their edges. 

 Dorsal arm-plates largely joined. Three tooth-papillee. Arm- 

 spines nearly smooth. (See p. 39.) 



Series III. 



In the following groups the oral shield is separated from the 

 side arm-plates by the adoral shields : 



Group H. — Ojyhiofora, gen. nov. Type. O. bartletti (Lym.) 



Tentacle-pores all large and open. No tentacle-scales. 

 (See p. 39.) 



*The two papilliform appendages of the first under arm-plate are 

 here supposed to be movable, but with the published figures and de- 

 scriptions it is not always possible to distinguish them from the solid, 

 immovable crest-like lobes, which are present on these plates in the 

 same position in many species, including O. bidentata. Among extra- 

 limital species, these papilla; are found in some species, such as O. ser- 

 rata Eym., that have the disk-scales and radial shields concealed. 



