JArANESE ASTEEOIDEA. 447 



mostly of six spines ; but since there are on many of the plates 

 one or two very small, rudimentary spines at one end it is possi- 

 ble that in larger specimens there may be more spines. The 

 spines are flattened and arranged like the fingers of the human 

 hand, the one at the middle being longest and those on either side 

 gradually decreasing in length. There is a small elongated pit at 

 the base of each spine (PL XY, fig. 230). In the outer row there 

 are mostly three spines, one very short thick and two large 

 flattened ones ; but on some plates the larger ones alone may be 

 present. The short spine, when present, always lie at the adcen- 

 tral end of the plate and may occasionally be represented by two 

 or more smaller spines, or again it may be entirely absent, or, 

 on the contrary, may be nearly as large as the other two spines, 

 which have sharp flattened edges. On the outer side of the outer 

 row of spines, between it and the first series of ventrolateral 

 plates, is a row, sometimes irregular, of somewhat w^edge- shaped 

 granules, five or six in number, and separated from the outer row 

 of adambulacral spines by a distinct groove, and from the first 

 series of ventrolateral plates by a narrow groove (PI. XV, fig. 

 231). At the adcentral end of each adambulacral plate, between 

 the inner and the outer row of spines is a forcipiform pedicellaria 

 of some size, occasionally with three jaws (PI. XV, fig. 233, 234). 

 It is sometimes situated exactly between two plates. 



Mouth-plates. — -The mouth-plates can not be observed from the 

 surface, but the spines are conspicuous and are arranged in two 

 rows. The inner row consists of seven or eight robust, prismatic 

 spines with rounded ends ; the spine at the oral end has the form 

 of a triangular prism, and together with its fellow form the apax 

 of the wedge-shaped figure formed by the oral spines ; the two or 



