792 " THETIS " SCIENTIFIC RESULTS. 



COMPSOMETRA INCOMMODA {Bell). 



Antedon, sp. nov., 1889, P. H. Carpenter, Proc. Roy. Soc. Vict., 



(N.S.), vol. 1, p. 135 {Port Phillip). 

 Antedon incoinmoda, 1888, Bell, Ann. and Mag. Nat. Hist. (6), 

 vol. 2, p. 404 (Port Pihllip).— 1889, Bell, idem, vol. 3, 

 p. 292 {supposed identity with A. puniila). 

 Compsometra lacertosa, 1910, A. H. Clark, Proc. U.S. Nat. Mus., 

 vol. 38, p. 275 (Port Jackson). 



Differential Characters. — Compsometra incommoda is a some- 

 what stouter species than C. loveni, the cirri especially being 

 stouter, with the three or four segments preceding the penul- 

 timate broader than long. 



Descrijjtion. — Centrodorsal discoidal, rather thin, with a broad 

 flat polar area nearly or quite 2 mm. in diameter; cirius sockets 

 arranged in two very closely crowded more or less irregular 

 marginal rows. 



Cirri xxxiv-xxxvi., 9-12 (usually 10) 7 mm. long, the extreme 

 flatness of the centrodorsal which, however, bears very numerous 

 cirri very closely crowded and almo.st in the same plane, short, 

 and rather strongly decurved distally, gives the dorsal part of 

 the animal a striking resemblance to certain species of Catopto- 

 metra or Oligometra, and renders it \ery unlike that of any other 

 macrophreate form. First cirrus segment very short, second 

 nearly or quite as long as broad, fourth and fifth the longest, 

 about half again as long as the median diameter ; following seg- 

 ments gradually decreasing in length so that the last two are 

 about as long as broad ; opposing spine minute, slender, sub- 

 terminal, directed slightl}' forward ; terminal claw long, nearly 

 twice as long as the penultimate segment, evenly tapering and 

 moderately and evenly curved. The second and following 

 segments are slightly constricted centrally, this character gradu- 

 ally disappearing distally as the segments become shorter ; the 

 longer proximal segments are rounded in cross section and 

 comparatively narrow in lateral view, but the segments become 

 laterally flattened distally and appear laterally broader, like the 

 cirri of Antedon petasus. 



■ Disk as in Compsometra loveni ; sacculi rather small but very 

 numerous along the ambulacra of the disk, arms, and pinnules. 



In good specimens the division series are entirely hidden by 

 the dense circlet of cirri ; radials even with the edge of the centro- 

 dorsal ; the I Br series extend outward horizontally as in 

 Com,atula so that the entire animal is flat as in the ten-armed 

 Comasterids ; I Brj^ very short, slightly ti'apezoidal, about four 

 times as broad as long ; I Br^ almost triangular, the lateral edges, 

 which are slightly shorter than those of the I Br^, making with 



