NAitRATix'K o ■" Bahama Exi'i-.dition. 



79 



nent •• cobble-stones."' and a still more prominent accessor\- 

 piece is placed in front of each side arm-plate, the latter being 

 considerably less conspicuous than the accessor\- piece. 

 There are two short, stubby arm-spines to each side arm- 

 plate, and a large tentacle-scale apparently- soldered down to 

 the lower arm-plate, there being no visible tentacle-pores. 

 The mouth-papilla.' are six on each side of each jaw, and they 

 too are apparently soldered together, a character of the genus 

 Of>/iioiuiisiiiiii. Another interesting fact is that the arms roll 

 in a vertical plane, a feature heretofore. I believe. obser\ed 

 onh- in the Astrophytida\ or basket-tish. This resemblance 

 is further helped out by the prominent ridges on the top and 

 sides of the arms, these ridges not being formed bv the upper 

 and side arm-plates. Indeed it is doubtful that this strange 

 ophiurian is an Ophioiiins/inii at all, and it may be regarded as 

 the tirst of a series of no less than eight species secured at 

 this station, which lead froni the true serpent-stars on the one 

 hand to the true branched Astrophytida^ on the other. 



The species above described would seem to be on the 

 serpent-star side of the line, still retaining the characteristic 

 mouth-parts, i. e.. mouth-shields, side mouth-shields and mouth 

 papilla?, combined with several features characteristic of the 

 rVstrophytida". 



Next in our progress toward the tvpical basket-tish. we 

 come to a species of Sigsbchu with a highlv vaulted disk 

 covered with harsh granules, and exhibiting pronounced 

 radiating ridges, and. in addition, raised ridges which form 

 concentric pentagonal markings, crossing the radiating ridges 

 at right angles. The bases of the arms are swollen, and the 

 arms throughout are ringed as in the next genus. The radiat- 

 ing ridges on the disk are formed not bv radial shields, but h\ 

 series of nodules or small plates. The arms are harsh with 

 rough granules arranged in ridges as in the next genus, and 

 roll naturally in a vertical plane, forming a stiff coil which can 

 hardly be unrolled after the animal is dead without breaking- 

 the arm. There are large and prominent accessory plates on 

 the sides of the arms. This species differs from Sfo-shcia 



