50 s. goto: 



from each other that the comparatively short spines of the two 

 adjacent plates do not come together at all. The exact fonction 

 of these pectinate pedicellarioe has yet to be determined by 

 observations on living specimens. 



Paxillœ. — The paxillse are comparatively small and those with 

 a large central spine are confined to the disk and the basal parts 

 of the arms. There are also more or less irregular series of 

 paxilla3 bearing small spines on either side of the arms at a 

 short distance from the superomarginals, each member of the 

 series being separated from the next by four or five paxillsB 

 without the large spine. These latter (PL I, fig. 7) are in general 

 more or less roundish in shape, except where the papular pores 

 are comparatively numerous, when the plates tend to assume more 

 or less a stellate form. The tabulum is very low, with a simply 

 rounded summit covered with some six to ten exceedingly small 

 granuliform spines without any distinction into centrals and 

 peripherals. In the paxillse with a central large spine the top of 

 the tabulum is more or less elevated and nearly hemispherical ; 

 tlie central spine is sharply pointed and in the disk may be as 

 long as 7 mm., but only 2 mm. or so at the outskirts of the 

 spinous area. The central spine is surrounded by a circlet of very 

 small spines, placed at a short distance from its base. The 

 papular pores are absent from the immediate vicinity of the anus, 

 but are quite numerous elsewhere in the spinous area. An 

 irregular series of these pores also extends along either side of the 

 arms close to the superomarginals, about three -fourths the length 

 of the entire arm. 



Structures similar to the pectinate pedicellarisG of the ventro- 

 lateral and inferomarginal plates are also found on the abactinal 



