OPHIUROIDEA OF THE BAHAMA EXPEDITION. 8 1 



mutilations, having lost about one-third of the disk and two 

 entire arms. The new arms are about one-half grown and 

 are perfectly formed. The new section of the disk is not 

 full grown and has a thinner skin, fewer and smaller spin- 

 ules and granules, and smaller and somewhat more irregular 

 radial ribs than the others. 



A young specimen from Station 62, with the disk 7.5 mm. 

 in diameter, agrees pretty closely with the larger ones in the 

 armature of the disk and arms, but on the disk the larger 

 granules are mostly short, conical, or obtuse; only a few of 

 them are acutely conical; the smaller ones are rounded grains; 

 on the arms the bands of granules are a little less numerous 

 than on the adult. There are four or live sharp, conical 

 mouth-papilkv, the outer one small. The granules of the low- 

 er and lateral surfaces are angular and flat, forming a smooth 

 mosaic; a single row of small conical spinules runs from the 

 base of one arm to another on the lower side, and at the up- 

 per margin of the interbrachial region there is a less regular 

 row of conical grains, so that the sides of the body, between 

 the arms, has a rigid, angular appearance. The smooth 

 granulation of the lower side of the disk extends directly out 

 on the lower side of the arms, concealing the plates. The 

 spines or tentacle-scales are mostly in threes, short, nearly 

 equal, oblong, thorny at the tips. 



Still younger specimens, from 2 to 3 mm. in diameter of 

 disk, from stations 13, 35 and 62, are quite different in ap- 

 pearance. In these the radial shields are naked, elevated, 

 and oblong-ovate, parallel, separated by one to three rows of 

 small, round granules; a radial row of three to five similar 

 granules extends out from the center in each interradial area; 

 the central area shows a central and live larger, obtuse-con- 

 ical, primary, radial granules and five primary interradials, 

 with many crowded smaller granules; two small round gran- 

 ules are situated on the outer end of each radial shield. The 

 granules of the upper side of the arm are small, round, and 

 prominent; about three rows alternate with the more ele- 

 V— 1 F 



