OPHIUROIDEA 189 



O. parcita Koehler (off Cape Verde, ca. 600 m., " Talisman " ; 

 only one specimen known) ; O. rosea Lyman (Bay of Biscay, 

 1410-1700 m., " Caudan " ; otherwise known from the Indo- 

 Pacific, 315-1400 m.) ; 0. setosa Miill. and Troschel (Bay of 

 Biscay to S. of the Canaries ; Mediterranean, ca. 50-1480 m.) ; 

 0. Smitti Ljungman (off Portugal, 1420 m., " Josefina " ; only 

 one specimen known) ; 0. Valenciennesi Lyman (Azores, Cape 

 Verde, 640-1440 m., " Talisman ", " Princesse Alice " ; also the 

 Malayan Ocean, ca. 200-1900 m.) ; 0. veterna Koehler (Azores, 

 Madeira, 1968-2200 m., " Princesse Alice "). The main characters 

 of all these species are given in the following key. On account 

 of the difficulty in sufficiently characterizing these numerous 

 species in the short terms of a key, where the use of some relative 

 characters cannot easily be avoided, reference is also given to 

 figures in some main works representing these various species ; 

 in order to make sure of the identification of such species as are 

 mentioned only in the key, it will be necessary to compare them 

 with the figures and descriptions in the works quoted. 



Key to the species of Ophiacantha known from or likely to 

 occur in the British seas. 



1. Two tentacle scales at one, two, or more of the proximal pore 



pairs ......... 2 



One tentacle scale, also at the proximal pore pairs . . 5 



2. Only first pore pair with two tentacle scales ; radial shields in 



a furrow ; disk with small stumps ending in a crown of 5-6 

 thorns ; ventral plates contiguous. 8 arm spines. {" Chal- 

 lenger^^ Ophiuroidea, PI. XV. 9-10) . O. cuspidata Lym. 

 The two proximal pore pairs, or more, with two tentacle 

 scales ......... 3 



3. Disk evenly granulated ; ventral plates contiguous. 7 slender, 



flattened arm spines. (" Challenger'' Oph., PL XXVI. 7-8) 



O. Valenciennesi Lym. 

 Disk with spines ........ 4 



4. Arm spines 6, flattened, serrate ; mouth shields wider than long, 



without spines. {"Hassler'' Oph., PI. II. 21-23) 



0. hirsuta Lym. 

 Arm spines 8, smooth, not flattened ; mouth shield longer than 

 wide, with spines along the outer edge (Fig. 105, 3, 4) 



1. O. spectahilis G. O. Sars 



5. Mouth papillae 5 or more on each side of jaw ; supplementary 



papillae may be present on apex of jaw or at the adoral 

 plates ......... C 



Mouth papillae 3-4 on each side of jaw ; no supplementary 

 papillae ......... 9 



