68 PROP. p. M. Duncan's beviston or the 



primary from the adoral suture of tlie compound plate is the 

 largest component. 



Interradia with, two or more vertical rows of primary tubercles, 

 which are large and otherwise similar to those of the ambulacra. 



Peristome with well-marked branchial incisions. 



Fossil. Oolite : Europe. Cretaceous : England, Europe, 

 Asia, W. Africa. 



Diplopodia is very interesting in the construction of the ambu- 

 lacral plates, which, when compound, are " diadematoid ;" on the 

 other hand, Fedinopsis, according to De Loriol, has the middle 

 plates of its compounds formed upon the '■'Echinus^'' type first 

 described by J. Miiller. 



Grenus Pedinopsis, Cotieau, 1863, Ech. Foss. de Pyren., Extr. de 

 Congr. Sci. de France, 28 Sess. Eordeaux, p. 16; 1879, Ech. 

 Foss. de V Alger, fasc. 5, p. 207 (P. Desori). Be Loriol, 1887, 

 Faune Cret. du Fort., Ech. fasc. i. p. 5-3, pi. x. figs. 7, a, h. 



Test moderate, thin, tumid, subconical, flat actinally. 



Ambulacra moderately wide ; pairs of pores biserial throughout, 

 or polyserial at the peristome, or uniserial at the ambitus ; inter- 

 poriferous area with two or more vertical rows of small perforate 

 and crenulate primary tubercles ; the compound plates high, 

 numerous, and the middle plate of each arranged with the others 

 upon the "Echinus^'' type. 



Interradial areas with numerous plates not much higher than 

 the compound ambulacral plates, with several or numerous rows 

 of small distant primary tubercles, resembling those of the am- 

 bulacra and diminishing in number abactinally. 



Peristome with feeble branchial incisions. 



Fossil. Cretaceous : England, Europe, !N". Africa. 



Genus Acabthechinus, Duncan Sf Bladen, 1882, Fal. Ind. 

 ser. siv., Foss. Ech. W. Sind, pt. ii. p. 34, pi. viii. 



Test turban-shaped, flat actinally. 



Ambulacra convex from side to side, one half of the breadth of 

 the interradia, with two vertical rows of primary tubercles ; pores 

 in numerous pairs, diplopodous apicaliy, in single series actinally, 

 very numerous, close, from five to eight pairs to a compound 

 plate ; zone narrowest actinally, slanting from the interporiferous 



