240 ECHINODERMS OF THE BRITISH ISLES 



is characterised by its broad arms, the rods of which are set 

 with rather long, at a right angle outstanding thorns. Is 

 especially common in August-September, but may be met with 

 throughout most of the summer. Regarding growth and age it 

 probably agrees with 0. texturata. A specimen was kept in an 

 aquarium for 2 years 8 months (Mobius). 



The young stage of a Trematode, F ellodistomum fellis (Olsson), 

 is found, to the number of 5-6, in the stomach of this Ophiuroid ; 

 the adult Trematode lives in the gall-bladder of Anarrhicas lupus, 

 whose food to a large extent consists of echinoderms. A 

 Cercaria (C. capriciosa Cuenot) has been found encysted in the 

 peritoneum. Further, young stages of Nematodes may be 

 found in the body cavity of this brittle-star, evidently belonging 

 to some species of Nematode living in fish. 



In the British seas this species occurs all round the coasts and 

 appears to be common everywhere in not too deep water. It is 

 distributed from East Finmark to the Mediterranean and the 

 Azores. It is rather euryhaline and therefore able to live also in 

 the Baltic (the western part, not beyond Bornholm). It is not 

 found at Greenland or the Atlantic coast of N. America. Its 

 bathymetrical distribution is ca. 4-850 m., but it is usually 

 confined to the region beyond ca. 200 m. 



4. Ophiura Ljungmani (Lyman). (Fig. 130.) 



(Syn. Ophioglypha Ljungmani Lyman ; 0. Thouleti Koehler.) 



Scales of dorsal side of disk rather fine ; the central plate 

 distinct, but the other primaries usually indistinct. Generally 

 some fine spines are found scattered on the disk. Radial shields 

 usually contiguous at the outer end. Arm comb consisting of 

 ca. 8-10 very slender papillae ; the secondary comb fairly distinct ; 

 2-3 somew^hat elevated dorsal plates within the notch/ the imier- 

 most with rounded outer edge. Arms rather high, somewhat 

 compressed, but scarcely roof-shaped on the dorsal side. Dorsal 

 plates longer than broad, elongate pentagonal. Ventral plates 

 widely separated, the outer edge convex, with a more or less 

 distinct prominence in the middle. Pores large ; the two 

 proximal pairs with several scales at both edges ; the scales at 

 the distal edge do not continue beyond the fourth, at the 

 proximal edge there are two scales beyond the fourth pair, and 



^ The figure erroneously shows only one very large dorsal plate within 

 the notch, the transverse lines indicating the limits between the plates 

 having inadvertently been omitted. 



