aENEKA A.VD GEOUPS OP TUE ECIIIS'OIDEA. 65 



Greuus Heteeodtabema, Cotteau, 1862, Bev. et Mag. de Zool. 

 ser. 2, vol. xiv. p. 200. De Loriol, 1887, 'Eaune Cret. du 

 Portug'., Ech. fasc. i. p. 44. (See V seudodiadema {Hetero- 

 diadema) Pseudo-Bourgeti, Cott. Pal. Eranc., Terr. Crefc. vol. 

 vii. pi. 1097.) {Amended.) 



Syn. Loriolia, JSTeumayr, 1881, Zeits. d. deutsch. geol. Gesellach, 

 Bd. xxxiii. p. 571 ; Colpotiara, Pomel. 



Test moderate, circular ia tumid ambital outline, subconical, 

 swollen but depressed abactinally, convex and rarL4y flat actinally. 



Apical system long, and wlien abseut leaving a large scar which 

 intrudes a considerable distance into the depressed posterior 

 interradium. When present, the madreporite is large and 

 passes from the right anterior basal plate to the centre of the 

 system and pushes backwards the periproct, which is bounded 

 by the postero-lateral basal plates and the postero-lateral radial 

 plates and one or two interradial plates. Moreover, the antero- 

 lateral radial plates separate the pairs of basal plates, and either 

 touch the madreporite, or come into the periproetal ring ; fifth 

 basal plate absent. 



Ambulacra with straight, narrow poriferous zones; the pnirs 

 of pores in simple series, except actinally, where there is some 

 doubling; plates compound (diadematoid). Tubercles of both areas 

 in vertical rows, moderate in size, very equal, perforate and cre- 

 nulated. Peristome flush, decagonal, with branchial incisions. 



Fossil. Cretaceous : Europe, N. Africa, Asia (Syria). 



Grenus Codiopsis, Agassiz, 1810, Cat. Sgsf. Ectgp. Ech. Foss. 

 p. 19. Desor, 1858, Synopsis., p. 112. De Loriol, 1887, Faime 

 Cret. du Portug., Ech. fasc. i. p. 57, pi. ix. {Amended.) 



Test moderate, swollen, high, often nearly globular, circular or 

 pentagonal in marginal outline; coronal plates numerous, high. 



Apical system small, solid. 



Ambulacra straight, narrow ; pairs of pores uniserial, in very 

 slight arcs; the plates low primaries, but near the pevi^^tome they 

 are compound, the middle component a large primary, and the 

 aboral and adcral components demi-plates. Primary tubercles of 

 both areas sn:all, smooth, nearly equal in size, and only occurring 

 actinally and lor a short distance towards the ambitus, a granu- 

 lation being eLsewhere. Periistome pentagonal, small, with slight 

 branchial incisions. 



Desor states that the primary tubercles are perforata', but they 

 are not so in available specimens. 



Fossil. Cretaceous : Europe, N. Africa, Ei^^ypt. 



LINN. JOUExV.— ZOOLOGl" VOL. XXIIT. 5 



