62 K. MITSUKUKI : STUDIES ON 



to the two dorsal ambulacral zones, these spots are arranged in 

 one, sometimes two, very conspicuous longitudinal rows. The 

 spots on these lines are not quite so circular as those in other 

 parts, but have their outer half flattened. Inside these lines, i.e., 

 in the median dorsal interambulacrum, the argus spots are very 

 thickly distributed, while outside the lines they are much more 

 sparse. Each of the spots is surrounded by a light space. 

 Inside tliis is a specially dark circle, which, while sharply defined 

 toward the outer rim, shades off gradually toward the centre of 

 the spot. Within the dark ring, the spot is yellowish in color, 

 and finally in the centre there is again a dark spot from which a 

 transparent papilla arises. The size and number of the argus spots 

 vary greatly with individuals. Some have rather small spots close 

 together, while others have larger ones more sparsely scattered. 

 Several of the argus spots may run together and form irregular 

 patches. This is especially the case around the anus. On each 

 of the anterior and posterior halves of the dorsum, mostly confined 

 inside the longitudinal rows of spots, is a large sooty black 

 patch. The ventrum is of the same ashy-white color as the 

 dorsum, and lias no argus spots. But in the anterior and 

 posterior halves, corresponding to the sooty black patches of the 

 dorsum, there are two large irregular straw-yellow areas. 



There are five groups of 30 — 50 small yellow papillae around 

 the cloacal opening, which in life is large and of a circular shape. 

 The papillae, which arise from tlie centre of argus spots on the 

 dorsum, lack the end-plates or have only little ones. In other parts 

 numerous appendages arise ; these have end-plates and must be 

 regarded as pedicels. On the ventrum are numerous pedicels 

 much more crowded than those on the dorsum. 



In the dorsal perisome, there are very delicate rosettes, some 



