BCHINODBEMAXA, 143 



doubt', -will be seen, when a large series is to hand, to be nothing 

 more than varieties of 0. rotata. As none of the arms are complete, 

 the measurements I could give might only be deceptive ; in them the 

 upper armnspines are proportionately larger than in the specimen 

 already spoken of; the bands separating the plates, the character of 

 •which has given rise to the specific name, may vary in breadth on one 

 and the same disk; and the granules may be in narrow or broad bands, 

 and may be so greatly elongated that they may more correctly be 

 spoken of as spines ; the marking would by some be spoken of as 

 exceedingly characteristic, for there extend from the disk on to the 

 arms two lines of dots of blue ; at every fourth plate, when regular, 

 , the two dots of either side fuse, and the spot enlarges into a blue 

 patch ; an exactly similar marking is to be seen on the lower sur- 

 face. In the specimen unhesitatingly placed with 0. rotata there is 

 not this definite arrangement of the dots. 



I have thought it right to direct attention to these peculiarities, 

 but a full and satisfactory discussion of the subject must be based 

 on a much larger series of specimens. 



These examples were also from Thursday Island. 



20. Ophiothrix pxmctolimbata. 

 Martens, Arch.f. Nat. 1870, p. 257. 



Port Curtis ; Port MoUe ; Thursday Island, 3-4 fms. ; Prince of 

 Wales Channel ; Warrior Keef. 



The specimen from Port Curtis, which is smaller than the others, 

 has the lateral spines proportionately longer, more echinulated, and 

 much more glossy. 



21. OpMothrix longipeda. 



Lyman, p. 35. 

 Port Curtis ; Port Molle. 



22. Ophiothrix microplax. 



Disk large, covered with short spines, less thick on the radial 

 shields ; ends of the not-thorny arm-spines faintly clavate. Pro- 

 portion of arms to disk about 6 to 1. 



The disk is rather large (20 millim. in diameter) and is covered 

 with very short spines, which may almost be described as spinous 

 granules ; these are not so closely packed on the radial shields or on 

 the actinal surface as on the rest of the disk. The radial shields 

 are small, elongated, triangular, the straight base of the one faces 

 that of the other ; the plates of each pair are separated by several 

 elongated scales, which carry a few longer spines. There is some 

 imbrication of the scales on the actinal surface of the disk. 



