362 COLLECTIONS FROM MELANESIA. 



lemon-yellow. The species has to be referred to Acabaria, as it 

 wants the foliated spicules (Blattkeulen) characteristic of Mopsella. 



Hab. Port Darwin, Australia, 8-15 fms. ; bottom mud. 



06s. The distribution of this species, hitherto known only from 

 Japan, is not by any means unparalleled (cf. Echinomuricea indo- 

 malaccensis, p. 336, extending from China to N.E. Australia) ; the 

 species has not hitherto been recorded from any point between 

 Australia and Japan. 



Dana's species (v. supra), from the Sandwich Islands, is probably 

 nearly allied if not identical with this, but the original description is 

 insufficient to decide the point. 



36. Acabaria serrata. 

 (Plate XXXVII. figs. E, E'; Plate XXXYIII. figs, c-c".) 



Corallum erect, branching dichotomously at angles of 30° to 40°, 

 strictly in one plane ; anastomosis absent or rare. Base ? Main stem 

 slender, not exceeding 2-5 millirn. in diameter. Internodes slender, 

 slightly flexuous, 8-10 millim. long as a rule, compressed from 

 front to back, decreasing slightly in diameter towards periphery, 

 viz. from about 1-5 millim. lateral diameter near base to *75 millim. 

 at tips of branches (exclusive of tubercles) ; antero-posterior diameter 

 only about half as great as the lateral diameter. Internodes 

 compact, apparently imperforate throughout ; axis deep crimson- 

 red. Soft joints distinct, spherical, nearly twice the diameter 

 (taken laterally) of the adjacent internodes, except near periphery, 

 where they are no thicker than the internodes ; substance compact, 

 deep crimson. 



Cortex very thin, but compact, smooth, deep crimson (in spirit) in 

 adult, white to pale scarlet in young specimens. Vomicae usually 

 forming a strictly single row down each lateral margin of the 

 branches ; in closed state rounded and but slightly prominent ; in 

 open state truncate-conical, about -5 millim. in height, serrating the 

 edges of the branches in a manner peculiar to this species in its genus ; 

 their bases are just free from each other ; colour (in spirit) pale yellow. 

 Spicules of cortex : — (i.) Fusiform or subclavate, curved, tnberculato, 

 one end usually well pointed, the other more or less obscured at one 

 side by projection of large tubercles ; tubercles distinct from each 

 other, but not arranged in whorls, long, pointed, rather ragged ; 

 those of the convex side very prominent towards the larger end 

 and inclined towards this end ; size -21 by -062 millim. (ii.) Smaller, 

 shorter, blunt or almost so, with thick shaft and two median whorls 

 of tubercles, low, rough, transversely elongated, forming almost 

 continuous ridges round the spicule, and a whorl of incipient tuber- 

 cles surrounding each, blunt end ; size "088 to - !2 by - U53 millim. 

 Spicules of verrucse : — (iii-) Horizontal, fusiform, curved, tapering 

 more or less, the middle beset with few. low, and rounded tubercles, 

 more or less roughened towards the ends ; size -21 to "25 by "024 

 to -035 millim. (iv.") Longitudinal spicules, apparently almost the 



