REPORT ON THE OPHIUROIDEA. 285 



not meet above, but project over the upper level of the arm, and bear a large, club-like, 

 rough spine, about 1"2 mm. long. Disk thin, and with deep constrictions in the inter- 

 brachial spaces. The smooth translucent skin allows the long and narrow radial shields 

 to be seen ; they are pointed within where they do not meet, and are separated their 

 entire length ; at their outer end they are elevated, and carry a jointed spine similar to 

 that of the arms. The first pair of armpores has no tentacle scales ; but those beyond 

 have two, which are thick and club shaped, with rough ends, and, unlike those of 

 Astroschema, are nearly equal in size, and not much elongated towards the middle of the 

 arm, where they bear bunches of minute hooks on their ends, and have a pedunculated 

 look, owing to the elongation of the side arm plates. Colour in alcohol, light yellowish- 

 brown. 



Station 235.— June 4, 1875 ; lat. 34° 7' N., long. 138° 0' E. ; 565 fathoms ; mud. 



Astronyx. 



Astronyx, Mull. & Tr., Syst. Ast., 1842. 



Disk large, arched, web 1 distinguished from the long slender, simple arms ; and, like 

 them, covered by a smooth, naked skin which obscures the underlying parts: the radial 

 shields may, however, be clearly made out, as slender ridges radiating from the centre of 

 the disk. Teeth, and tooth papilke similar and spiniform, as are the few mouth papillae. 

 Side arm plates like little pads bearing hooked arm spines, and connected by a small 

 shapeless under arm plate. Sides and top of arm quite naked, there being no upper arm 

 plates. Two small genital openings in a depression at the inner angle of the interbrachial 

 space. 



On removing the skin this genus is found to have well-marked side mouth shields, 

 and, in their open angle, is a minute mouth shield ; one of them, larger than the rest, is 

 the madreporic plate, which Miiller and Troscher correctly located, though they did not 

 recognise it as a mouth shield. The peristomial plate is large, transverse oval, and in a 

 single piece. The long narrow radial shields are broken in pieces, somewhat as in 

 Astrophyton. They are attached to very wide fiat genital plates, to whose inner end is 

 fastened a small plate which may be the genital scale. 



Species of Astronyx not herein described. 



Astronyx loveni, Mull. & Tr., Syst. Ast., p. 119, 1842. 

 North European Seas ; Japan ; 350 fathoms. 



(ZOOL. CHALL. EXP. — PART XIV. — 1882.) 37 



