234 THE VOYAGE OF H.M.S. CHALLENGER. 



and three inner sides short. Side arm plates broad and thin, meeting near base of arm, 

 neither above nor below. The place of the upper arm plates is occupied by thick skin, 

 through which may be distinguished the upper side of the arm bones. Disk flat and 

 thin, covered with a thick, slightly wrinkled skin, which conceals the radial shields and 

 the fine scahng, though the latter may be distinguished in the lower interbrachial spaces. 

 Genital scales quite hidden. Genital opening extending from the mouth shield to the 

 margin of the disk. Three cylindrical, stout, nearly equal, pointed arm spines, about as 

 long as an arm joint. One small rounded tentacle scale on inner side of the tentacle 

 pore. Colour in alcohol, grey. 



I admit this species to Ophioscolex with some hesitation. The mouth papilla are 

 different in shape and arrangement; but the absence of upper arm plates and the 

 characteristic covering of smooth skin suggest its position. 



Station 24. — March 25, 1873; ofi"Culebra; 390 fathoms; mud. 



Species of Ophioscolex not herein described. 



Ophioscolex coppingeri, Bell, Proc. Zool. Soc, Jan. 1881, p. 98, pi. viii. fig. 6. 

 West Coast Patagonia. 



Ophioscolex glacialis, Mull. & Tr., Syst. Ast., p. 109, 1842, pi. xlii. figs. 2-4. 

 Arctic European Seas and North America; 100-300 fathoms. 



Ophioscolex purpureus, Diib. & Kor., Of. Skandinav. Echin., p. 235, 1844 ; Ljn. 

 Oph. Viv. Of. Kong. Akad., p. 327; Lym., Bull. Mus. Comp. Zool., vol. v. part 9, 

 p. 233. 



West Indies ; 190 fathoms. Norway. 



Ophioscolex stimjysonii, Lym., 111. Cat. Mus. Comp. Zool., No. viii., part 2, p. 23, 

 1875 ; pL i. figs. 11-15. 



Off Sombrero Key, Florida ; 240 fathoms. 



Ophiambix. 



Ophiamhix, Lym., Anniv. Mem. Bost. Soc. Nat. Hist., 1880. 



Disk flat ; arms wide and flat ; and both beset above with sharp grains, or spines. 

 No radial shields or upper arm plates externally visible. Small, sharp, mouth papillae 

 and teeth ; no tooth papillje. Tentacle pores very large. Side arm plates widely 

 separated above and below, but occupying a considerable part of under surface of arm. 

 Arm spines translucent, hollow, and with an uneven surface. 



