OPHIUROIDEA 



187 



ca. 1100-1400 m. (" Helgca "). It is further known from the 

 Skagerrak and off the Azores and Madeira, and from W. Green- 

 hind to S. CaroUna. The bathymetrical distribution is ca. 250- 

 ca. 1500 metres. 



2. Ophiotoma Lyman. 



(Syn. Ophiopora Verrill.) 



A rather thick skin covers the scales of the disk, leaving only 

 the outer end of the radial shields naked. Arms not covered by 

 thick skin, the arm plates being distinct. Tentacle pores rather 

 large ; no tentacle scale, except at the pore of the second mouth 

 tentacle. Mouth papillae simple, papilhform. 



Only one species known from British (and European) seas. 



1. Ophiotoma coriacea Lyman. (Fig. 104.) 



Disk rather thick, the small scales being hardly visible through 

 the skin, though more distinct on the oral side. A few scattered 



Fig. 104. — Ophiotoma coriacea; part of dorsal and oral side, x 3. 

 (After Lyman, " Blake " Oph.) 



spinelets are found on the disk. Dorsal plates of arms con- 

 tiguous, with outer edge convex ; ventral plates separated by 



