ORDER II EUECHINOIDEA—DIADEMATOIDA 229 
bo 
small, smooth, primary tubercles. dmb tubercles replaced abactinally by 
warty or irregular elongate elevations. Epistroma much developed. Abun- 
dant in Upper Jura. 
Family 3. Diadematidae. Wright. 
Test highly ornamented, tumid, depressed, or spheroidal. Ambulacra straight, 
moderately broad or narrow, with vertical 
rows of small primary tubercles, and com- 
pound plates near the ambitus and actin- 
ally. Interambulacra broad, with numer- 
ous low plates; the rows of primary 
tubercles diminishing in number dorsally. 
Peristome large, polygonal. Lias to 
Recent. 
D 
‘Sub-Family A. DIADEMATINAE. 
Ambulacral plates compound near the 
ambitus ; pairs of pores in simple vertical 
series or in ares of three. 
Diadema,Schynvoet(Pseudodiadema, 
Desor), (Fig. 368). Amb narrow, often 
projecting ; two vertical rows of small, 
primary, crenulate, and _ perforate 
tubercles extending from peristome 
ee apes LAmb with JO) he MEDS Diadema (Pseudodiadema) neglectum, Thurm, From 
vertical rows of primary tubercles the Bernese Jura. A, B, Profile and ventral aspect of 
resembling those of the Amb, but test, 1/;. C, Ambulacrum, enlarged. D, Spine, 1/1. 
larger. Secondary tubercles and granules surrounding the scrobicules. 
Spines long, hollow, longitudinally striated. Lias to Recent. 

Fic. 368. 
Duncan has shown that the separation of the fossil species from the recent under Desor’s 
term of Pseudodiadema is a purely artificial distinction. The following sub-genera are 
recognised:—Centrostephanus, Peters ; Recent. Microdiadema, Cotteau ; Lias. Diademopsis, 

Fic. 369. 
Codiopsis doma, Desm. sp. Cenomanian (Tourtia); Tournay, Belgium. 4, Side-view of test, 1/;. B, Ventral 
aspect of same. C, Apical system, enlarged. 
Desor; Lias. Lchinodiadema, Cotteau; Upper Jura. Hemipedina, Wright; Jura, Cretaceous, 
and Recent. The latter differs from Diadema in having simple Amb plates near the apex, 
and perforate, but not crenulate tubercles. 
Heterodiadema, Cott. Like Diadema, but with the apical system greatly 
