REPORT ON THE OPHIUROIDEA. 237 



Ophiogeron edentulus, Lym. (PI. XII. figs. 10-18), Bull. Mus. Comp. Zool., vol. v., 

 part 7, p. 161, pL vii. figs. 187-189, 1878. 



Two or three feeble pointed teeth ; otherwise the mouth angle quite naked. Two 

 stout arm spines, which, stripped of skin, show longitudinal rows of hooked thorns. 



(Type specimen from Station 175.) Diameter of disk 3 mm. Length of arm about 

 14 mm. Width of same close to disk, without spines, 1 mm. Mouth angles quite 

 naked, except one small pointed papilla at apex of jaw and two or three more that 

 represent teeth. Mouth shields rounded triangular ; length and breadth about equal, 

 with an angle within, and outer side rounded. Side mouth shields rather large, curved, 

 longer than wide, broadest within, where they meet. First under arm plate narrow, 

 five-sided, with inner edge straight, a broad angle without, and re-entering curves on the 

 lateral sides, second plate similar, but narrower and with the angle inward. Those 

 beyond are further modified by having the outer and inner sides curved. Side arm 

 plates broad and meeting below, beyond the second under arm plate ; flaring somewhat 

 toward their outer edge. The arm plates and mouth shields are more or less obscured by 

 thick skin. Along the upper side of the arm the central ridge of the arm bones shows 

 through the skin. Disk flat and thin, completely covered with a naked wrinkled skin. 

 Two short tapering arm spines, which when stripped of skin present longitudinal rows of 

 slightly hooked thorns. No tentacle scales, but large pores from which long smooth 

 tentacles protrude. Colour in alcohol, greyish. 



Station 76.— July 3, 1873; hit. 38° 11' N., long. 27° 9' W. ; 900 fathoms; 

 globigerina ooze. Station 175.— August 12, 1874; kit. 19° 2' S., long. 177° 10' E. ; 

 1350 fathoms ; red clay. 



r 



Ophiohelus. 



Ophiohelus, Lym., Amiiv. Mem. Bost. Soc. Nat. Hist., 18S0. 



Disk covered with a delicate, film-like scaling, without radial shields. Arm bones 

 composed of two halves like curved bars, lying side by side, joined at their ends and 

 enclosing an oval hole. Mouth papillae spiniform and arranged in a single row ; teeth 

 similar ; no tooth papillae. On the outer joints of the arm. the true arm spines cease, 

 and are replaced by two or more rows of minute spines or pedicellarise, which have the 

 form of a long-handled parasol. 



Ophiohelus pellucidus, Lym. (PI. XXVIII. figs. 5-9). 



Opkiofa Ins pellucidus, Lym., Anniv. Mem. Bost. Soc. Nat Hist., pi. i. tigs. 11-15, 18S0. 

 Parasol spines short and stout ; in two rows, three or four in a row. Disk smooth. 

 No tentacle scales. 



(zool. CIIALL. EXP. — PART XIV. — 1882.) O 31 



