REPORT ON THE OPHIUROIDEA. 229 



of the jaw pierced with a vertical hole. Iiiterbrachial spaces somewhat swelled. Two 

 large genital openings beginning outside the mouth shields. 



The skeleton belongs strictly to the group of Ophiothrix with its peculiarities 

 exaggerated. Thus the special apophysis extending outwards from the outer surface of 

 the arm bones is larger and more spreading, so that it really is locked into the slot in the 

 following bone (PI. XLII. fig. 14). The upper surface of the arm bones is, moreover, 

 longer, and, together with the margin, is deeply grooved. In general appearance the 

 genital plate is like that in Ophiothrix, and its scale (n), seen edgewise in the figure, has 

 a corresponding shape. The high and deeply grooved wings of the mouth frames (/) 

 are a further exaggeration of the type, and the regular and very large radial shields are 

 quite as important as in Op>liiothrix suensonii. Fig. 15 shows a mouth angle and two arm 

 joints from the under side, and exhibits the separation of the two halves of the jaw (c) 

 characteristic of the OpMothrices, together with the cup-like socket {r') of the second 

 mouth tentacle. 



See Plate XLII. figs. 14, 15. 



Species of OpMociiemis not herein described. 



Ophiocnemis marmorata, MilU. & Tr., Syst. Ast., p. 87, 1842, pi. xlii. figs. 14, 15 ; 

 Lym., 111. Cat. Mus. Comp. Zool., No. i. p. 152 ; Bull. Mus. Comp. ZooL, vol. iii., part 10, 

 p. 234. 



Opliiura marmorata, Lmk., Hist. Anim. sans Vert., vol. ii. p. 543. 



Ophiothrix dypeata (yoimg), Ljii., Opli. Viv. Of. Kong. Akad., p. 163, 1866. 



Great Ocean. 



Opihioniaza. 

 Ophiomaza, Lym., 111. Cat. Mus. Comp. ZooL, No. vi., 1871 



Disk above covered by very large naked radial shields and by plates. On the 

 interbrachial spaces below, a fine scaling. Numerous crowded tooth papillas forming a 

 vertical oval. Teeth. No mouth papillae. Arm spines numerous, rounded, not trans- 

 lucent, solid. The base of the jaw pierced with a vertical hole. Interbrachial spaces 

 somewhat swelled. Two large genital openings beginning outside the mouth shields. 



The skeleton belongs strictly with the Ophiotlirices, and most resembles that of 

 Ophiocnemis. 



Ophiomaza cacaotica, Lym., 111. Cat. Mus. Comp. ZooL, No. vi., p. 9, pi. i. fig. 15, 

 1871 ; Bull. Mus. Comp. Zool., vol. iii., part 10, p. 233. 



Station 187.— September 9, 1874; lat. 10° 36' S., long. 141° 55' E. ; 6 fathoms; 

 coral sand. 



(zool. CHALL. EXP. — PART XIV. — 1882.) 30 



