208 ECHINODERMS OF THE BRITISH ISLES 



material, especially from deeper water, in order to secure all the 

 species present. The very numerous species within this family 

 are divided, mainly according to the number of the mouth papillae, 

 into several genera, four of which are represented in British (and 

 European) seas. Two other genera are known from off Cape 

 Verde, viz. Ophiostigma Liitken, with the species 0. africanum 

 Lyman, and Amphilimna Verrill, with the species A. (Ophiocnida) 

 libera (Koehler), but as both are littoral forms there is scarcely 

 any prospect of finding them as far north as the British coasts, 

 and no further mention of these two forms is needed here. 



Key to the genera of Amphiuridce known from the 

 British {and European) seas. 



1. One outer mouth papilla on each side of jaw, not contiguous with 



the infradental papillae ...... 2 



Two outer mouth papillae on each side of jaw, contiguous with 

 the infradental papillae ; the outermost very broad, scale - 

 hke ...... 4. Afnphipholis Ljungm. 



2. Scales of ventral side and on margin of dorsal side of disk each 



ending in a small tubercle ; radial shields with a transverse 



furrow , , . . . .2. Acrocnida Gislen 



Scales smooth ; radial shields without transverse furrow 3 



3. Apparently two pairs of plates between adoral plates and infra- 



dental papillae . . . .3. Paramphiura Koeliler 



Only one pair of plates (the jaw, generally apparently unpaired) 

 between adoral plates and infradental papillae 



1. Amphiura Forbes 



1. Amphiura Forbes. 

 (Syn. Ophiopeltis Diiben and Koren.) 



A single -mouth papilla (exceptionally two) on each side of 

 jaw at the outer end of the mouth slit, widely separated from 

 the infradental papillae. Deeper on each side of jaw is seen a 

 single, centrally- directed papilla, belonging to the first tube-foot 

 (this papilla is not counted among the mouth papillae proper). 

 Arms very long, slender, and very flexible. Disk scales not 

 spinous or thorny. Generally, the disk is somewhat incised 

 above each arm. 



Six species of this genus have been recorded from the British 

 seas, but several more are more or less likely to be found there, 

 namely: Amphiura ahyssorum Norman (55° 10' N., 25° 58' W., 

 3210 m., " Valorous " ; only one specimen known) ; A. digna 

 Koehler (19° 19' N., 20° 22' W., 2320-2330 m., " Tahsman " ; 

 only one specimen known) ; A. grandis Koehler (Bay of Biscay, 



