234 ECHINODERMS OF THE BRITISH ISLES 



Pacific, from S. Africa to Japan, the smallest depth from which 

 it is recorded being 96 m. ; 0. Grubei Heller, known from the 

 Mediterranean and the Atlantic coasts of Morocco, 10-20 m. ; 

 0. imprvdens (Koehler) (Syn. Ophioglypha imprudens Koehler),i 

 from ofif the Azores, 560 m. (only one specimen known ; 

 " Talisman ") ; 0. inermis (Lyman) (Syn. Ophioglypha inermis 

 Lyman), found S. of the Canaries, 1786 m. (" Princesse 

 Ahce "), known elsewhere from off Tristan d'Acunha, 900 m. 

 (" Challenger ") ; 0. irrorata (Lyman) (syn. Ophioglypha irrorata 

 Lym. ; 0. mundata Koehler, 0. orhiculata Lyman ; 0. involuta 

 Koehler ; 0. tumulosa Ltk. and Mrtsn. ; 0. grandis Verrill), 

 found in the Bay of Biscay (" Caudan ", '' Talisman "), and off 

 the Canaries (" Talisman "), otherwise of cosmopolitan distri- 

 bution in warm and temperate seas, ca. 600-4315 m.) ; 0. lepida 

 (Lyman) (sjoi. Ophioglypha lepida Lyman), found off the Azores, 

 1620 m., S. of Iceland, 2060 m. (" Thor "), also known from 

 the Atlantic coasts of N. America, ca. 1000-2235 m. The following 

 key gives the main characters (with reference to figures) of all 

 these species, together with those actually known from the 

 British seas. 



Key to the species of Ophiura Tcnown from or likely to occur 

 in the British seas. 



1. Ventral plates in proximal part of arm separated by pores ; 



outer arm comb with numerous (ca. 30) papillae 



1. O. texturata Lmk. 



No pores between proximal ventral plates ; outer arm comb 



with fewer (7-15) papillae, or rudimentary, or continuous 



across base of arms, or absent ..... 2 



2. First dorsal plate divided by a longitudinal line in two lateral 



halves . . . . . . 6. 0. carnea M. Sars 



First dorsal plate not divided by a longitudinal line . . 3 



3. Arm combs absent. (" Challenger " Oph. PI. VII. 4-6) 



0. inermis (Lym.) 

 Arm combs continuous across base of arms. (" Siboga'' Oph., i. 



PI. VIII. 7-9) O. Clemens (Koehler) 



Arm combs small, rather indistinct ; mouth shields short and 



broad ^ ......... 4 



Arm combs well developed ...... 5 



^ This species is referred by H. L. Clark to the genus Amphiophiura ; 

 in the opinion of the present author it more naturally belongs with the 

 genus Ophiura proper. 



^ Perhaps O. concreta should rather be reckoned to the group with small, 

 indistinct arm combs ; from the two other species of the group, O. robusta 

 and irrorata, it is easily distinguished by having the four proximal ventral 

 plates broadly contiguous and nearly quadrangular. 



