OPHIUROIDEA 217 



6. Amphiura securigera (Diiben and Koren). (Fig. 122, d-f.) 



(Syn. Ophiopeltis securigera Diib. and Koren ; Amphiodia 

 securigera (Diib. and Koren).) 



Disk completely naked, both on dorsal and ventral side, with 

 the sole exception of the radial shields, which are narrow, parallel, 

 and contiguous in their whole length (Fig. 122, e). Dorsal arm 

 plates fan-shaped, with convex outer edge and an obtuse angle 

 within, well separated, the proximal ones rudimentary ; ventral 

 plates pentagonal, with straight outer edge. Three, in the proximal 

 part of arm 4, arm spines, the second from below strongly axe- 

 shaped widened at the point. No tentacle scales, or, at most, a 

 single small scale here and there at a pore in the distal part of 

 arms. Mouth shields rounded triangular. Outer mouth papilla 

 small, more or less pointed ; often two small papillae are found 

 here. Colour in Ufe olive-green or brownish -green on disk, the 

 radial shields whitish ; arms dark brownish, in the proximal 

 part somewhat Hghter coloured. Diameter of disk scarcely 

 exceeding ca. 5 mm. Arms very long, twelve to fifteen times 

 the diameter of disk, usually very strongly coiled up. 



Development unknown. It appears that this species prefers 

 a hard bottom, and conceals itself among shells or the like. 



In British seas this species has been found off Shetland, 

 70-90 m. (Norman), 61° 10' N., 5° 46' W., 290 m. (" Mchael 

 Sars ") ; also the " Porcupine " found it in the Faroe Channel. 

 It has further been found off Eddystone, ca. 50 m. (the author). 

 It is elsewhere known only from the Norwegian coast, as far 

 north as Lofoten, and from the Faroes. Bathymetrical dis- 

 tribution ca. 40-600 m. 



2. Acrocnida Gislen. 



Scales of ventral side of disk and at margin of dorsal side 

 produced into a small tubercle, giving a slightly spinous appear- 

 ance ; no real spines on disk. Radial shields with a transverse 

 furrow near the distal margin. ^ Ventral plates of arms longi- 

 tudinally furrowed. 



One species known from the British seas ; another species, 

 A. neapolitana (M. Sars), occurs in the Mediterranean, and a third 

 species, A. semisquamata (Koehler), on the West African coast. 



1 In Fig. 123 this transverse furrow on the radial shields has 

 inadvertently been omitted. 



