SHALLOW-WATER STARFISHES 323 



rays, with broadly curved interradial margins. Radii, 10 mm. and 

 32 mm. ; ratio, 1 : 3.2. 



Upper marginal plates regular, not very large, a little convex, nar- 

 row and encroaching very little on the dorsal side in the interradial 

 angles, but on the rays becoming more conspicuous, as seen from 

 above, slightly oblique, squarish. The two rows at the middle of the 

 ray are separated by a space only about equal to the width of a plate ; 

 they are regularly and uniformly and closely covered by small, erect, 

 divergent, blunt, rough spinules, and separated by narrow, deep, 

 finely fasciolated grooves. 



ad 



FIG. 15. 



Bunodaster ritteri Verrill, type. Portion of under side of a ray; ad, adambulacral spines; 

 a, a' , two rows of interactinal plates and spines; m, m, two inferomarginal plates and spines 

 enlarged. 



FIG. 16. 



Bunodaster ritteri Ver., type. A group of dorsal plates and papular pores from middle of 

 the base of a ray, seen from the inside, much enlarged. 



The dorsal surface is covered with rather large, round, mostly 

 equal, convex, stellate paxillae, each covered with a large number of 

 regularly divergent, small, nearly equal, obtuse, rough spinules, of 

 which the larger have from twenty to thirty. Those at the margins 

 form simple, deep fascioles. When the spinules are removed, the 

 plates are in the form of low, round-topped or nearly hemispherical 

 bosses, mostly nearly equal in size and form, with only a few smaller 

 ones, here and there, and separated by intervals of flexible integu- 

 ment, with about six papulae standing singly and regularly around 

 each plate. The papulae are lacking on a small central area of the 



