EEPOET ON THE OPHIUROIDEA. 165 



Ophiostigma africanum, Lym. (PI. XVIII. figs. 17-19). 



Ophiostigma africanum, Lym., Bull Mus. Comp. Zool., vol. vi., part 2, p. 41, pi. xiii. figs. 

 368-370, 1879. 



Arms more than eight times the diameter of disk. Outer mouth papillae very wide. 

 Radial shields long, narrow, and joined. 



(Type specimen from Cape de Verde Island.) Diameter of disk 2 '2 mm. Length of 

 arm 18 mm. Width of arm near disk '6 mm. Three mouth papillae on each side of a 

 mouth angle, whereof the two inner ones are small, short, and almost conical, while the 

 outer is straight and very wide, extending from the first under arm plate about two- 

 thirds the length of an angle. Mouth shields three-sided, with rounded angles, bounded 

 without by a curve, and within by a rounded angle ; length to breadth, "2 : 'S. Side 

 mouth shields wide, a little broader without than within, where they fully meet. Under 

 arm plates small, pentagonal, with outer side nearly straight, lateral sides a little 

 re-enteringly curved, and an angle within. Side arm plates nearly meeting above and 

 below, and having a thick, low, spine crest. Upper arm plates small, irregular trans- 

 verse oval, with the inner curve deeper than the outer. Disk rather thick, standing 

 nearly clear of the arms, as is usual in the genus : covered with fine, thin, nearly equal, 

 indistinct scales, whereof most are rounded, but some, near the centre, are angular : there 

 are about twelve in the length of 1 mm. where they are finest. Along margin of disk 

 are minute, peg-like, scattered spines, which are not jointed at the base. Radial shields 

 long, narrow, and closely joined ; length to breadth, "6 : "2. At their outer ends are 

 visible the points of the genital plates, in two little lobes. Three stout, equal, peg-like, 

 very short arm spines, standing nearly at right angles with the arm. Two minute, 

 longer than broad tentacle scales standing diagonally with the arm plate. Colour in 

 alcohol, nearly white. 



St. Vincent, Cape de Verde Islands. 



Ophiostigma africanum difiiers from Ophiostigma isacanthum in having longer arms, 

 and longer, narrower radial shields ; and from Ophiostigma formosa by its wide outer 

 mouth papilla and longer arms. 



Species of Ojjhiostigma not herein described. 

 Ophiostigma isacanthum, Lym. (PI. XLII. fig. 16). 



Ophiostigma isacantlaim, Lym., 111. Cat. Mus. Comp. Zool., No. i. p. 103, figs. 8, 9, 1865; BuU. 



Mus. Comp. Zool., vol. v., part 9, p. 224. 

 Ophiiira isacantha. Say, Journ. Phil. Acad., voL v., p. 150, 1825. 

 Ophiostigma moniUfor-me, Ltk., Addit. ad Hist., part 2, p. 132, 1859. 



West Indies ; littoral to 63 fathoms. 



(zool. chall. EXP. — PAET XIV. — 1882.) 22 



