OPHIUROIDEA 223 



contiguous at their outer end, diverging inwards. Dorsal arm 

 plates nearly transverse oval, well separated ; ventral plates 

 pentagonal, with slightly excavated outer edge, well separated. 

 Three slender arm spines ; no tentacle scales. Mouth shield tri- 

 angular-rounded ; two mouth papillae on each side of jaw, the outer 

 one very broad, scale-like. Colour in life bluish- or brownish- 

 grey on centre of disk, the edge and the arms generally light 

 yellowish. Reaches a size of ca. 7 mm. diameter of disk ; arms 

 ten to twelve times as long as diameter of disk. 



It lives on mud bottom, probably buried in the mud in the 



Fig. 126. — Amphilepis norvegica. Part of dorsal side (1) and oral side (2). 

 X 8. (From Danmark's Fauna.) 



same way as the Amphiuras. Otherwise nothing knowTi of its 

 biology or development. A species of Loxosoma is not rarely 

 found attached to its oral side. 



In British seas this species has been found off S.W. Ireland, 

 ca. 940-1765 m. (" Helga ") ; further, it was taken at various 

 stations in the Faroe Channel by " Michael Sars ". It is else- 

 where distributed from Lofoten to Skagerrack on the Scan- 

 dinavian coasts, and towards the south to the Bay of Biscay 

 and S. of the Canaries ; also in the Mediterranean. It is also 

 known from the east coast of North America, but not from Green- 

 land. Bathymetrical distribution ca. 100-2900 m. 



VIII. Family Ophiochitonidj5 



Disk usually with very small naked scales. A number of 

 mouth papillae contiguous with the infradental papilla, which 

 may be single, well developed, or apparently double, rudimentary. 

 A single series of teeth ; no tooth papillae. Second pair of tube- 

 feet inside the mouth edge. Tentacle scales large, leaf -like. 

 Arms rather stout ; arm spines slender, more or less distinctly 

 erect. 



Only one genus of this family known from the British seas. 



