GENEEA AK^D GEOTJPS OF THE ECHINOIDEA. 5S 



The genus Circopeltis origiuated with M. Pomel, 1883, but his 

 definition was not a positive one ; he compared it with Leiosoma. 

 M. de Loriol has, however, shown that the genus is not related 

 to Leiosoma but to Goniopygus. 



Genus Ciecopeltis, Pomel, 1883, Theses Class. Method. Ech. 

 {Alger), p. 89. De Loriol, 1887, Faun. Cret. du Portug., 

 JEch. fasc. i. p. 55, pi. ix. fig. 7. 



Test small, subhemispherieal, depressed dorsallj, flat aetinally. 

 Interradial plates few (8-9). 



Apical system solid, with or without radial plates entering the 

 periproctal ring ; peiiproct large and subcircular. 



Ambulacra straight, expanding near the large tubercles, broad 

 at the peristome, tho interporiferous area with primary tubercles 

 in two vertical rows, large at the ambitus, and smaller aetinally, 

 and smallest and distant abactinally, all are plain; poriferous 

 zones with uniserial pairs of pores abactinally, in slight arcs near 

 the large tubercles, and sbghtly crowded aetinally ; plates low, 

 broad, simple primaries abactinally, compound at the ambitus and 

 aetinally, the adoral component a demi-plate and its pair of pores 

 much nearer the median line than the other pairs, excluded from 

 the ambulacro-interradial suture. The other components long ; 

 low primaries with an occasional demi-plate. 



Interradia with two vertical rows of plain primary tubercles, 

 largest at the ambitus ; rows of secondary tubercles and granules. 



Peristome moderate, with branchial incisions. 



Fossil. Cretaceous : Europe, N. Africa (?). 



The compound ambulacral plates are not without an affinity 

 with those of the recent Aspidodiadema, A. Agass. 



Genus Cidaeopsis, Cotteau, 1860 (reference not to be found). 

 1882, Fal. Fran^., Terr. Jura, livr. Ivi. p. 433, pis. 376, 377. 



Test moderate and rather small in size, swollen above and 

 almost flat below, circular in outline at the ambitus. 



Apical system solid and moderately developed. 



Ambulacra subflexuous abactinally, enlarging at the ambitus, 

 having small primary tubercles aetinally which are smaller than 

 those of the interradia, perforate and crenulate. Towards the 

 apex the tubercles are replaced by granules. Poriferous zones 

 undulating, with simple pores, close, and they multiply near the 

 peristome. 



