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



SympagcUa mix also appears in Milne-Edwards' list, published in 1881, of the 

 specimens collected by the " Travailleur " on the coasts of Spain and Portugal. 

 This genus contains only one species. 



Sympagella nux, 0. Schmidt (PI. XXII. figs. 4-9). 



The much injured specimen of Sympagella nux, 0. Schmidt, which is figured in 

 PI. XXII. fig. 4, was obtained on coralhne mud in the neighbourhood of the island of 

 St. lago, one of the Cape Verde Islands, from a depth varying from 100 to 128 fathoms. 

 The body is branched like the horns of a stag, and from its round principal stem, which is 

 1*5 mm. in thickness, two somewhat bent more delicate side branches arise on the same 

 side. The upper extremity of the principal stem, which is broken ofi' beneath, forms an 

 oval body, which is 1 cm. long and 6 mm. broad. The superior transversely truncated 

 extremity of the latter bears the orifice (2 mm. in width) of a simple gastral cavity. The 

 latter is slightly narrowed towards the base of the body, and ends blindly without being 

 continued into the stalk. While the outer surface of the body-wall (which is 2 mm. in 

 thickness) is surrounded by a continuous skin, through which small cavities can be seen 

 only here and there, larger efi"erent passages appear on the inner surface, and open 

 directly into the gastral cavity. It is indeed possible that the gastral membrane may 

 have been torn or otherwise injured where it extended over the inner openings of the 

 efferent canal system. The upper lateral branch exhibits the lower fragment of a torn- 

 ofi" body. 



The principalia of the parenchjnnal skeleton consist, as in Aulascus, of simple, regular, 

 moderately strong hexacts, with somewhat rough pointed extremities, and of numerous 

 diacts, varying in strength, length, and direction. In these the centre swelling sometimes 

 exhibits four cruciately disposed knobs, sometimes an annular elevation, or sometimes 

 only the merest trace. The diacts are straight or slightly bent, and run out to similar 

 points at both ends. A slight roughness frequently occurs in the neighbourhood of the 

 terminal points. 



With regard to rosettes, discohexasters are particularly abundant in the parenchyma, 

 and are provided with short principal rays, and long diverging terminals uniformly thin, 

 or slightly thickened towards the outer end. The latter are smooth or very slightly 

 roughened, and terminate in a watch-glass-shaped arched disc, provided with six to eight 

 marginal prongs. Each principal ray bears three, or less frequently four, terminal rays. 

 These are strong at the base, diverge in an arch-like curve, and then continue in a 

 straight or slightly bent course. 



Besides these discohexasters, the plumicomes which are found in Aulascus johnstoni 

 also occur, but I have found them only in scattered distribution. Finally, the parenchyma 

 contains here and there peculiar structures, which Oscar Schmidt called " roller stars " 



