242 ART. 2. — H. MATSUMOTO: 



concave lateral edges corresponding to the radial shields, outer 

 edges very long and concave corresponding to the first lateral arm 

 plates, and terminating with a very acute outer angle. The 

 elevated plates have slightly raised margins, so that the surface 

 is concave. Radiais shaped like maiden hair, with a semicircular 

 inner border and concave outer sides corresponding to the radial 

 shields, and with an acute outer angle ; longer than wide. Radial 

 shields irregularly triangular, with perfectly rounded angles, convex 

 inner and shghtly concave outer borders ; about as long as wide, 

 hardly touching each other. Dorsal arm plates seven or eight in 

 number, confined to the pentagonal body. The first one is 

 triangular, wider than long, smaller than but as wide as the next 

 plate. The following plates, which become smaller outwards, are 

 quadrangular, with truncated outer angles, wider without than 

 witliin ; the second to the fourth plates are wider than long. All 

 the plates are in contact with one another, except the last one or 

 two, which are very rudimentary and isolated. Within the 

 pentagonal body, the lateral arm i^lates are much elongated 

 laterally, with the width almost equal to the length of the 

 corresponding arm joints, lightly bent outwards, striated parallel 

 to the axis of elongation. They meet with the corresponding 

 dorsal arm plates, except the first, which is separated ù'om the 

 first dorsal by the radial shield. The first lateral arm plates of 

 the neighbouring radii are apposed to each other distally, outside 

 the second interradial. The distal edges of the successive lateral 

 plates form a continuous line, the interradial borders of the 

 pentagonal body, which are shghtly indented, and hemmed by a 

 series of soldered papillas, which are evidently the modified arm 

 spines of the modified lateral arm plates. These papillge are longer 

 towards the middle of the interradial borders, where they are 



