JAPANESE A8ÏER0IDEA. 459 



mostly simple, but there are also many compound ones, composed 

 of two or three parts. There may be as many as seven pedicel- 

 la rife on one plate, counting the compound ones as single. 



Ad amhul acred platesi. — The adambulacral plates are short and 

 nearly square in form, but can not be seen from the surface. The 

 armature consists of three rows of spines and a few pedi- 

 cellaria9, and the rows are well separated from each other, the 

 top of the innermost series nearly coinciding with the base of the 

 second row, and the outermost series being separated from the 

 middle row bv a distinct OToove. The innermost row consists of 

 eight or nine slender brittle spines arranged like the fingers of the 

 hand, the middle one or ones being longest and the lateral ones 

 shorter, the terminal ones on either side being frequently very short. 

 Near the mouth the difference in length of these spines is less 

 great, and on the first adambulacral plate they may form a 

 straight comb. The second row of spines is separated from the 

 first by a relatively large space, and there are either two or three 

 of them, except on the first plate, which may carry four. The 

 spines of this row are usually very unequal both in size and 

 shape. When there are only two, they may be subequal in size 

 and shape, or one of them, may he considerably smaller than the 

 other. When there are three they are, as a rule, of unequal size 

 and shape, one, usually the middle, being considerably larger, and 

 one considerably smaller than the remaining medium sized one. 

 The well developed spines of this series are flattened and spatu- 

 late in form, narrower towards the base and with a wedge-shap- 

 ed, more or less longitudinally grooved truncated end. When 

 there are three the smallest one may be very slender and only 

 half as long as the largest. The spines of the outermost row 



