vuw. 11.] MADEIRA TO THE COAST OF BRAZIL. 63 



had got before, so that no further light was thrown upon the 

 curious question of its occurring in that peculiar semi-niineral- 

 ized state at so great a depth. 



I give here a preliminary notice, under the name of Ophia- 

 oantha chehjs (Figs. 16 and 17), of a pretty little brittle star 

 which was found clinging to several of the branches of coral. 

 It is, however, so different in aspect from such typical s^iecies 

 of the genus as O. spmulosa and O. setosa that I have some 



Fia. 17. — Ophiacantha chehjs, Wyville Thomson. Oral aspect of the disk. Four times the 

 natural size. (No. 87.) 



hesitation in associating it with them ; indeed, I should scarcely 

 have done so had it not been that the described form which 

 approaches it most nearly is undoubtedly Ophiacantha stellato,^ 

 Lyman. I think it very likely that when we have an opportu- 

 nity of studying the mass of new material which has been pour- 

 ing in for the last three or four years, it may be found necessary 

 to reconsider the genera of the Ophiuridea as at present defined, 

 and to revise their limits. The diameter of the disk in Ophia- 

 cantha chehjs is, in an ordinary example, 8 mm. ; the width of 

 the arm near the base 2 mm., and the arm is about three and a 

 half times the diameter of the disk in length. The disk is in- 

 cised in the centre of the space between the arms so deeply as 



