288 s. goto: 



SuperomarcjinaU. — The superomarginals are exactly like the 

 paxillœ, and tlierefore will not be treated of separately. 



Inferomarginals. — The inferomarginals are comparatively large 

 plates forming the lateral margin of the arms and lying between 

 the adambulacral and superomarginal plates. In a cross-section of 

 the arms it occupies nearly two-thirds of the space between the 

 ambnlacral furrow and the superomarginals, the remaining one- 

 third being occupied by the adambulacral plates. The armature 

 of the inferomarginals varies slightly in different specimens and 

 on different plates of the same specimen. Most usually there are 

 four large conspicuous spines making a single transverse series 

 among themselves and with the large spines of the adambulacrals 

 (PI. V, fig. 83). These large spines of the inferomarginals are 

 separated from one another by smaller spines, some of which may 

 become large enough to form a series with the larger ones, so that 

 the number of the latter usually varies between three and five. The 

 smaller spines are mostly grouped along the margin of the infero- 

 marginal plate, but are also present more or less between the larger 

 spines, as stated above. The fasciolar gooves between the infero- 

 marginal plates are well developed especially in the outer part, 

 and are covered with capillary spinelets. Müller and Tkoschel 

 state that the larger spines of the inferomarginals form 2-3 

 longitudinal series on the arms ; but in all the specimens ex- 

 amined by me these longitudinal series are too irregular to 

 deserve the name, with perhaps the exception of the outermost 

 spines, which show a tolerably regular longitudinal arrangement. 

 The inferomarginals may bear one or more biscuspid pedicellariae, 

 as described by Kœhlee. 



Adambulacral plates. — The adambulacral plates are tolerably 



