532 " THETIS " SCIENTIFIC RESULTS. 



3 specimens from near Sydney. 

 2 specimens from Lord Howe Island. 



It is interesting to note that while the specimens from near 



• Sydney have eleven rays each, those from Lord Howe Island 



, have only seven. It would be much more interesting to know 



what the average number is for each locality and what degree of 



variation is shown. This would afford an admirable subject for 



, a biometrical investigation. 



COSCINASTERIAS DUBIA,!^ sp. nov. 



(Plate xlix, figs. 3 and 4; pi. 1.) 



Rays 5. R=;83 mm., r=16 ram., R=5r. Interbrachial arcs 

 acute. Rays somewhat flattened (markedly so in dried specimens), 

 with sides vertical and actinal surface sharply marked off. 

 Breadth of ray near base, 20 mm, Disc moderate or small 

 vertical diameter, 9 mm. Rays slightly constricted where they 

 join disc. Whole abactinal surface provided with conspicuous 

 slen ler spines, 3-5 mm. high, each surrounded at its base with a 

 dense wreath of minute pedicellarise. There are about twenty of 

 these spines on the disc, where they are smaller than those on 

 the rays. The latter are arranged in five fairly regular longi- 

 tudinal series, the median one containing about thirty spines, the 

 marginal about twenty each, and the intermediate about ten 

 each. Abactinal skeleton rather stout, with relatively small 

 spaces, each showing about half-a-dozen papulse or fewer. At 

 base cf arms and on disc, scattered irregularly among the spines, 

 are large solitary pedicellarise (PI. xlix., fig. 2) about 2 mm. long. 

 Similar pedicellarise, but scarcely half so large, occur on many of 

 the wreaths of minute pedicellarise surrounding the spines (PI. xlix., 

 fig. 3). Adambulacral armature consists of two more or less 

 cylindrical spines about 3 mm. long, standing one directly outside 

 the other, so that two very distinct rows of adambulacral spines 

 are conspicuous. Near the mouth, these spines are larger and 

 are decidedly flattened at tip. Actinal surface of ray, outside of 

 adambulacral armature^ more or less covered by three series of 

 spines, so arranged as to form oblique rows of two or three each, 

 . of which the marginal is decidedly the largest and most adoral. 

 These marginal spines are about 5 mm. long, and for fully half 

 their length are united to each other by a membrane, which thus 

 forms a conspicuous marginal fringe to the actinal surface of the 

 ray. Each spine is very much flattened and widened at the tip 



12 rfu?>i£i= doubtful, in reference to the close resemblance to Asterias 

 eustyla. 



