188 ECHINODERMS OF THE BRITISH ISLES 



the lateral plates, with convex outer edge. Ann spines 4-5, 

 slender, smooth. Mouth shield wide triangular, with rounded 

 corners. Mouth papillae 5-6 to each side of jaw. Reaches a 

 considerable size, ca. 17 mm. diameter of disk, the arms being 

 ca. five times as long as the diameter of disk. Colour in alcohol 

 greenish -grey on disk ; arms pale brown. 



In British seas this species has been found only at 51° 22' N., 

 12° 41' W., 1765 m. (" Helga "). It is elsewhere known from off 

 the Azores (" Princesse Alice ") and from the West Indies 

 (" Blake "). Bathy metrical distribution 530-3465 m. 



3. Ophiacantha Miiller and Troschel. 

 (Syn. Ophiolimna Verrill.) 



Disk covered with fine thorns or stumps ; radial shields 

 wholly covered or just the outer end visible, or quite small, but 

 distinct. Tentacle pores small and inconspicuous, with one or 

 two simple tentacle scales. Mouth papillae simple, papiUiform. 



Six species of this genus are known from the British seas, but 

 several more are very likely to occur there also, viz. 0. anomala 

 G. O. Sars (known from Norway, Greenland, and off Nova Scotia, 

 ca. 200-1400 m.) ; 0. Bairdi Lyman ("Talisman," 2400-2600 m. ; 

 locality not given ; known elsewhere from off the Atlantic coast 

 of U.S. America, and widely distributed in the North Pacific ; 

 bathymetrical distribution ca. 620-2600 m.) ; 0. brevispina 

 Koehler (only one specimen known, from Bay of Biscay, 166 m. 

 (" Hirondelle ") ; 0. composita Koehler (syn. 0. simulans 

 Koehler) (Bay of Biscay, off the Canaries, 1480-2083 m., 

 " Caudan," " Talisman " ; also the Indo-Pacific, ca. 700-2800 

 m.) ; 0. cuspidata Lyman (off Ascension, 785 m., " Challenger " ; 

 Mediterranean, 2460 m., " Princesse Alice ") ; 0. decipiens 

 Koehler (off the Azores, 1257 m., " Talisman " ; only one 

 specimen known) ; 0. hirsuta Lyman (off Madeira, 1500 m., 

 " Princesse Alice " ; otherwise known from the West Indies, ca. 

 150-ca. 800 m.) ; 0. lineata Koehler (off the Azores, 1165 m., 

 " Princesse Alice " ; also off Florida, 490-990 m.) ; 0. mesembria 

 H. L. Clark (syn. 0. meridionalis Koehler (non Lyman), 0. 

 pentagona, var. armata (Koehler) (off Azores, 2870 m., " Hiron- 

 delle " ; otherwise known from the W. Indies, ca. 250-1125 m.) ; 

 0. nodosa Lyman (S. of Canaries, 3145 m., " Challenger " ; only 

 one specimen known) ; 0. notata Koehler (off N.W. Spain, 1226 

 m., " Talisman " ; only one specimen known) ; 0. opercularis 

 (Koehler) (syn. Ophiolimna opercularis Koehler) (12° 7' N., 33° 33' 

 W., 6035 m., " Princesse Alice " ; only one specimen known) ; 



