274 



ECHINODERMATA— ECHINOZOA 



PHYLUM IV 



Orthocidaris Cotteau. Apical system small, pentagonal. Amb narrow, 

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

 granule. lAmb very broad, numerously plated. Primary, 

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

 ceous ; Europe. 



Temnocidaris Cotteau. Upper Cretaceous. Polycidaris 

 Quenst. Upper Jura. 



Section B. Amhulmral Pore-pairs Biserial. 



Diplocidaris Desor. Test large, spheroidal. A^nb narrow, 

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

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

 column. Primaiy tubercles large, perforate, scrobiculate. 

 Upper Jura ; Europe. 



Tetracidaris Cotteau (Fig. 384). Remarkable in having 

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

 diminishing to two at the apex. Ar)ib straight, moderately 

 broad. Poriferous areas depressed, pairs incompletely 

 biserial ; interporiferous areas narrow, granular, with a row 

 of plain small tubercles, placed near the borders of the 

 poriferous zone. lAmh primary tubercles very large, 



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



remien); Europe. 



Fig. 383. 



I'orocidans schmiedeli 

 Goldf. Nnmmulitic 

 Limestone; Mokkatain, 

 near Cairo. /.4m;) plate 

 and sjiine. 



Fni. 384. 



TetiucUlarin reynesl Cotteau. Neocomian ; Vergans, near Castellane, Bas.ses AliJSS. A. Test reduced 

 one-half. /?, Portion of Jm/j, enlarged (after Cotteau). 



Xenocidaris Schultze. Founded upon clavate, fusiform spines from the 

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



Orders. CENTRBCHINOIDA ^ Jackson. 



Test regular, endocyclic, two columns of plates in each amhulacral area, 

 amhulacral plates compound, rarely simple; two columns of plates in each inter- 



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

 Crustacean. 



