228 ECHINODERMS OF THE BRITISH ISLES 



Two genera are represented in the N.E. Atlantic, namely : 

 Ophiernus Lyman, with the species 0. adspersus Lym., found at 

 20° 38' N.,^20° 40' W., 1160-1230 m. ("Talisman"), and 0. 

 abyssalis Koehler, found off the Azores, Madeira, and the north- 

 west coast of Spain, ca. 1670-1970 m. (" Princesse Alice "); ^ 

 Ophiocrates Koehler, with the species 0. secundus Koehler, found 

 south of the Canaries, 2325-2638 m. (" Talisman "). The two 

 genera are thus distinguished : 

 Second tentacle pore visible from the outside ; tentacle scales 2-3, 



only partly concealing the large pores . Ophiernus Lym. 



Second tentacle scale not visible from the outside ; one tentacle 



scale, which wholly conceals the pore . Ophiocrates Koehler 



The two species of Ophiernus are thus distinguished : 



Ventral plates only half as wide as the lateral plates 



O. adspersus Lym. 

 Ventral plates not narrower than the lateral plates 



O. abyssalis Koehler 



IX. Family Ophiolepid.^.^ 



Disk covered on both sides with scales, which are usualty naked, 

 rarely more or less concealed by the skin. Mouth papillae forming 

 a continuous series ; a single series of teeth, no tooth papillae. 

 Second tube-foot inside or outside the mouth edge. Arm spines 

 appressed, mostly small and more or less rudimentary. Arms 

 usually rather short, often with combs of papillae at the base. 



Four genera of this large family are known from the British 

 seas, but seven more genera are likely to be represented there also, 

 namely : Amphiophiura Matsumoto, with four species (see below, 

 p. 230) ; Aspidophiura Matsumoto, with the species A. minuta 

 (Lyman) (Syn. Ophioglypha minuta Lyman), one specimen taken 

 in the Bay of Biscay, 1710 m. (" Caudan "), this species being 

 otherwise known from off Crozet Island and south of Australia, 

 2415-3240 m. ; Homalophiura H. L. Clark, with two species 

 (cf. p. 231); Ophiomisidium Koehler, with the species 0. pul- 

 chellum (Wyv. Thomson) (Syn. Ophiomusium pulchellum Wyv. 

 Thorns.), taken off Portugal and south of the Canaries, 946-1916 m. 



^ In the " Challenger " Ophiuroidea Lyman records another species, 

 Ophiernus vallincola Lym., from off the Azores (1800 m.). It is highly 

 probable, as pointed out by Koehler, that Lyman in reality had the species 

 later on described by Koehler as 0. ab;/ssalis before him, but failed to recog- 

 nise it as different from the nearly related 0. vallincola, which occurs in the 

 Antarctic Sea. 



^ Perhaps more correctly " phiolepididce ". 



