458 s. GUTü : 



Supcromargiaals. — There are twenty-four of these, and they 

 are invisible from tlio abactinal side except in the last third of 

 the arms. In the iiitorbrachial arcs they lie entirely on the actinal 

 aspect of the body and thence gradually emerge on to the lateral 

 margin towards the terminal part of the arms. As seen from 

 the surface the lirst snperomarginal i)late on either side of the 

 interradial line is larger than the others and has a prolonga- 

 tion toward the abactinal side, the upper end of which articulates 

 with one of the abactinal plates. The second plate has a much 

 shorter triangular prolongation ; a few plates at a short distance 

 from the apex of the arms have also similar prolongations, but 

 all the rest are destitute of any, and present a decidedly convex 

 surface towards the outside, especially in the basal part of the 

 arms. The superomarginals are closely covered over with rather 

 coarse, flattened granules and mostly bear one or a few trans- 

 versely elongated, valvate pedicellariœ, which are very conspicuous 

 to the naked eye. On some of the plates there may be as many 

 as five of these pedicellarioe, and they may measure as much as 

 3 mm. in length. 



Infrromarginals. — The inferomarginal plates are entirely con- 

 fined to the actinal aspect of the body. In the intorbrachial arcs 

 they are more or less elliptical or rectangular in form, but in the 

 arms they are either roundish or irregularly pentagonal. They 

 are mostly coincident with the superomarginals, but in the more 

 distal part of the arms they have a tendency to become alternate 

 with them. They are completely invested with granules exactly 

 like those of the superomarginals, and bear roundish or more 

 or less transversely elongated valvate pedicellariœ, which are 

 usually more numerous than on the superomarginals. They are 



