274 



ECHINODERMATA— ECHINOZOA 



PHYLUM IV 



Orthocidaris Cotteau. Apical System small, pentagona!. Amb narrow, 

 straight ; pore-pairs in simple straight series, the pores separater! by a 

 granule. lAmb very broad, numerously plated. Primary 

 tubercles small, piain, perforate and distant. Lower Creta- 

 ceous ; Europe. 



Temnocidaris Cotteau. Upper Cretaceous. Polycidaris 

 Quenst. Upper Jura. 



Section B. Amhulacral Pore-pairs Biserial. 



Diplocidaris Desor. Test large, spheroidal. Amb narrow, 

 straight. Pore-pairs very numerous, close, alternating more 

 or less. lAmb broad, with seven to eight plates in each 

 column. Primary tubercles large, perforate, scrobiculate. 

 Upper Jura ; Europe. 



Tetracidaris Cotteau (Fig. 384). Remarkable in having 

 four columns of plates in each lAmb at the ambitus, but 

 diminishing to two at the apex. Amb straight, moderately 

 broad. Poriferous areas depressed, pairs incompletely 

 biserial ; interporiferous areas narrow, granulär, with a row 

 of piain small tubercles, placed near the borders of the 

 poriferous zone. lAmb primary tubercles very large, 



crenulate and perforate. Spines narrow, elongate. Lower Cretaceous (Bar- 



remien); Europe. 



Fig. 383. 



Forocidaris schmiedeli 

 Goldf. Numraulitic 

 Liniestone; Mokkatain, 

 nearCairo. lAmb -plate 

 and spine. 



Fi(i. 384. 



Tetracidaris reynesi Cotteau. Neocomian ; Vergans, near Castellane, Basses Alpes. A, Test reduced 

 one-half. B, Portion of Amh, enlarged (after Cottean). 



Xenocidaris Schnitze. Founded upon clavate, fusiform spines from the 

 Devonian of the Eifel. Incompletely known, possibly belongs in this family. 



Order 3. CENTRBCHINOIDA i Jackson. 



Test regulär, endocyclic, two columns of plates in each ambulacral area, 

 ambulacral plates Compound, rarely simple; two columns of plates in each inter- 



^ This name is based on Gentrechinus, a new narae for Diadema which was preoccupied for a 

 Crustaceaii. 



