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are in a line, all borne close to the angular edge of the 

 plates, and may be absent from a few plates near the tip of the 

 arms. On the first inferomarginal plate the spine is but little 

 removed from the middle of the edge, but in all the rest it is 

 attached near the distal end. Occasionally there are two spines 

 on one plate. The inferomarginal plates bear transversely elonga- 

 ted valvate pedicellariœ, exactly similar in form to those of the 

 superomarginals, but usually larger. Many of the more elongated 

 ones show one or a few constrictions, showing clearly that they 

 were formed by the coalescence of two or more pedicellariae. 

 There are indications that these constituent pedicellariae are again 

 formed by a linear fusion of two series of granules, each valve 

 consisting in fact of many granuliform portions. In some cases 

 there may be as many as three or four constrictions on a single 

 pedicellaria. There are also some in which the constituent parts 

 stand at a considerable angle to each other. The pedicellariœ of 

 the marginals, both superior and inferior, are exceedingly low and 

 scarcely rise above the general surface of the granules by which 

 they are surrounded. 



Adamhulacrals. — The adambulacral plates are narrow and com- 

 paratively long and their boundary towards the ventrolaterals is 



* 



not very distinct, so that the first series of the latter are apt to 

 be mistaken for the adamhulacrals. The armature is simple and 

 very characteristic : the furrow series consists of 5-7 spines with 

 rounded ends arranged in a palmate form and connected to- 

 gether close to the base by a web-like membrane (PL XlII, 

 fig. 213) ; the spines are, however, usually so close together 

 that the connecting membrane is not conspicuous. On the 

 actinal surface at the outer end of the plate on a low tubercle 



