206 



AP.T. 2.— H. MATSUMOTO : 



lateral and outer angles, about 

 as wide as long. Adorai shields 

 also small, triangular, with con- 

 cave adradial side, longer than 

 wide, tapering inwards, nearly 

 meeting with each other in 

 the interradial line. Oral plates 

 rather short, very narrow. 

 There is a small, naked, de- 

 pressed space between the adorai 

 shields and the oral plates of each 

 oral angle. Two oral papillae on 

 either side ; the distal one, arising 

 from the adorai shield, is very 

 large, oval, fiat, thin and leaf-hke ; 

 the apical one is infradental, 

 small, short, very thick. Teeth quadrangular and thick. 



Arms stout in comparison to the disk diameter, more or less 

 cylindrical, wider than high, very gradually tapering outwards. 

 Dorsal arm plates fan-shaped, with convex outer border, wider 

 than long, wider outwards than inwards ; the surface is nearly 

 level longitudinally, but decidedly convex transversely. Lateral 

 arm plates rather high, those of the two sides not meeting 

 with each other above or below, except in the very distal arm 

 joints ; they are almost covered over by the arm spines. First 

 ventral arm plates not very small, pentagonal, wider than long. 

 Those beyond hexagonal, with the shortest inner lateral sides 

 and longest and convex outer border, lateral sides concave, 

 corresponding to the tentacle pore ; about as long as, or longer 

 than, wide, widest at the outer ends of the tentacle pores, faintly 



Fig. S6. Amphiura iridoides. x 14. a. 

 From above. l>. From below, c. Side 

 view of three arm joints near disk. 



