278 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the dorsal surface of the disk are furnished with elongated and nu- 

 merous spines. The distal portion of the radial shields shows a light 

 blue spot and their surface is also studded with dark blue points. 

 The arms show blue striae which are alternately longer and shorter ; 

 the shorter consist of an elongated and narrow blue line, the longer 

 of dark blue dots immersed in a light blue spot. 



The other specimens are also very typical, excepting that from 

 station 5401. I figure this last (pi. 33, figs. 1, 2). The diameter of 

 its disk varies between 13 and 14 mm., and the arms are very much 

 more elongated than usual, their length reaching at least 80 mm.; 

 they are extremely slender in their distal third. The radial shields 

 are very large and the rest of the disk is covered with extremely 

 short spines. The radial shields show dark blue dots with a more 

 or less developed light blue spot toward the distal extremity. The 

 colored dots on the arms do not form the type of striae to which the 

 species owes its name ; instead of these there occurs toward the distal 

 border of each upper arm plate two dark blue dots surrounded by a 

 clearer ring ; sometimes another dot occurs somewhere on the surface 

 of the plate. 



I have thought it best to record the peculiarities which this speci- 

 men shows, though they evidently are not sufficient for separating it 

 from the others. The most important difference is found in the arms, 

 which are very much longer than usual ; as for the dimensions of the 

 radial shields, they are susceptible of very great variation in O. 

 striolata. In my collection I have an O. striolata from the Sunda 

 Archipelago in which these radial shields are as large as in the speci- 

 men from station 5401; the spines of the dorsal surface are very 

 much more developed than in the latter, though they are very much 

 less numerous than in the specimen from station 5146, and the arms 

 are not longer than usual. I include a photograph of the dorsal sur- 

 face of this specimen (pi. 34, fig. 5). I also give a photograph of 

 some spines from the dorsal surface of the disk of the specimen from 

 station 5146 (pi. 102, fig. la). The hook formed by the first ventral 

 arm spine has the usual form and show* three or four branches (fig. 

 Id) . The tentacle scale usually ends in a rather strong point to which 

 there may be added one or two others smaller ( b ) . 



Ophiothrix striolata has been found in different localities in the 

 Indian Ocean, and it scarcely ever leaves the littoral region; the 

 Siboga met with it in the Sunda Archipelago at depths varying from 

 12 to 59 meters (7 to 33 fathoms). 



