188 ART. 2. — H. MATSUMOTO : 



four times as long as the disk diameter and the ventral arm 

 plates have a convex outer border and rounded outer lateral angles, 

 while in the Neapolitan specimens, the arms are two and a half to 

 three times as long as the disk diameter and the ventral arm 

 plates have straight outer border and not rounded outer lateral 

 angles. The difference in the arm length may not be very 

 important in the question of the distinctness of the two species, 

 because in A. sqiiamata the arms are said to vary from two and a 

 half to four and a half times as long as the disk diameter. I there- 

 fore look upon the difference in shape of the ventral arm plates as the 

 only distinctive character of the present species as compared with 

 A. squamata. In the shape of the ventral arm plates, the present 

 species much resembles A. australiana Clakk, but differs from it 

 in the more numerous disk scales of the dorsal side and coarser 

 disk scales of the ventral side. The radial shields have each a 

 white spot at the outer end, as in A. squamata. 



The present species is common in the neighbourhood of Misaki 

 and is found living under stones in fine sand. As to its sensitive- 

 ness to the coarseness of the sand, I made the following observa- 

 tions at Aral Beach. In the summer of 1910, there were at first 

 among the rocks numerous spots covered with fine sand, and this 

 species was found very abundantly ; but after a tempest, it was 

 reduced to small numbers, owing to the fact that the spots with 

 fine sand became very scanty. In the summer of 1911, spots with 

 fine sand were very scanty, and this species was also few. In 

 the summer of 1912, the beach was entirely covered with coarse 

 sand, and the species could not be found any longer. This 

 ophiuran is very quick in motion, and can instantly conceal itself 

 in the sand, when the stone is turned up. 



The present species is undoubtedly viviparous like ^l. squamata. 



