ECHINODBEMATAj 141 



broader than long. Six arm-spines, the uppermost the longest, as 

 long as two or three arm-plates, swollen at thoir tip, only faintly 

 thorny. One tentacle-scale. 



Disk with a large number of bine patches and dots ; arm-platos 

 above faint reddish pink, with clots of blue at the sides, and broad 

 transverse bands of blue at regular intervals. Colour-markihgs 

 below less pronounced. 



Port Jackson, 0-5 fins. 



14. Ophiothrix caespitosa. 

 Lyman, Chall. Rep. p. 218. 



Though the ' Challenger ' found but few representatives of this 

 species, it is apparently one of the most common in the neighbour- 

 hood of Sydney. 



Port Jackson, March 1881. 



15. Ophiothrix martensi. 



Lyman, p. 86. 



If I am right in ascribing to this species examples from Thursday 

 Island and Port Darwin, it is one which must be regarded as exhi- 

 biting very remarkable variations in coloration. The original spe- 

 cimens, collected by Prof. Semper in the Philippines, were described 

 by Mr. Lyman as being in colour, " above, bright indigo, with a 

 darker line along the arm, bounded by a lighter one on either side ; 

 below, paler indigo, with a white line along the arm." In a smaller 

 specimen, " the blue lines along the arms were continued to the 

 centre of the disk, but wore not margined by lighter lines." In the 

 two specimens collected on "Aug. 7, 1874" (in the neighbourhood 

 of the Fiji Islands), by the ' Challenger,' and determined by Mr. 

 Lyman, I observe that there is a faint indication of a white line on 

 either side of the blue lines on the disk, and that the white line 

 on the ventral surface is, at places, broken across by a patch of 

 indigo. 



On either side of these " typical specimens " there would appear 

 to be a light and a dark variet}-. In the latter the whole creature 

 may be deep purple, the two white lines on the arms being at regu- 

 lar distances invaded by purple patches of such a size as to leave only 

 spaces of white equal to themselves ; and as these patches are sym- 

 metrical on either side of the middle line, the original white lines 

 come to be represented by nothing more than paired patches of white ; 

 similarly the white line below disappears, or rather is forced out to 

 the sides, and appears only as a thin marginal line. The light 

 variety is no less interesting ; with the exception of the radiating 

 lines, the disk above is altogether white, and even these lines may 



