OPHIUBANS OF THE PHILIPPINE AND ADJACENT WATERS. 109 



narrow proximal border, diverging sides very strongly excavated by 

 the tentacle scale, and a very broad and convex distal border ; this last 

 passes over into the sides by very prominent rounded angles, almost 

 as broad as the tentacle scales of which they simulate the outline in 

 such a way that in a superficial examination of the arms one might 

 believe that two successive tentacle scales are present. The second 

 plate is in contact with the first, but beyond this these plates are 

 separated by a space which is occupied only on the sides by the side 

 arm plates, the middle being filled with soft tissue. The side arm 

 plates show a much elevated ridge, which, at the base of the arms, 

 carries nine spines, this figure falling to eight and then to seven. 

 These spines are cylindrical, rather stout, with the extremity obtuse 

 and rounded ; their length increases from the first ventral, which is 

 almost as long as two segments, to the antepenultimate, which is 

 almost equal to four segments ; the last spine is usually a little shorter. 

 Their surface is rugose, and under the microscope very fine and very 

 closely crowded asperities may be made out, which become more 

 marked toward the extremity of the spine. The two lateral rows of 

 spines come very close together in the dorsal median line, but they are 

 not, however, continuous with each other, remaining separated by the 

 proximal angle of the upper arm plates. These spines are solid. 



The tentacle scale is single, except on the first segment, on which 

 the pores have two scales, the external a little the smaller; it is not 

 very large, and is oval in form, a little longer than broad. 



The general color of the specimen is light red; the plates of the 

 dorsal surface of the disk with their granules are darker. The radial 

 shields are irregularly bordered with dark gray ; a straight line, also 

 dark gray, extends along the middle of the dorsal surface of the arms 

 throughout their entire length. The two surfaces of the arms as well 

 as the spines are light red, becoming a little darker in the terminal 

 part. The ventral surface of the disk is roseate, darker in the in- 

 terradial spaces. 



Affinities and distinctive features. — It seems to me that this 

 ophiuran must be placed in the genus Ophiomitra in the restricted 

 sense as adopted by Verrill, because of the presence of tooth papillae 

 and the solid spines, but it differs notably from several species as- 

 signed to that genus, and also to related genera in its very robust 

 structure, in the considerable development of the spines, in the form 

 of the under arm plates, and in its coloration, which gives it an ap- 

 pearance recalling that of an Ophiothrix. It shows some resemblance 

 to the species described under the name of Ophiomitra, spinosissima 

 by H. L. Clark, which comes from Porto Rico, but this last is not an 

 Ophiomitra in Verrill's sense, and it seems to me rather to represent 

 the type of a special genus. 



