ORDER I 



ASTEROIDEA EUASTERIAE 



209 



occur with large, tuberculous plates on the abactinal area, which are often 

 armed with powerful spines. Upper Jura to Recent. 



Sphaerites, Quenst. Under this title are included detached hexagonal 



Fio. 340. 



Metopaster Purkinsoni. Forbes sp. Lower Chalk ; Sussex. A, Ventral aspect. B, Viewed from one side 

 (after Forbes). 



plates of variable size and thickness, which are of not uncommon occurrence 

 in the Jura of Wurtemberg and Switzerland. Some of them bear strong 



Fio. 341. 



FIG. 342. 



Sphaerites scutatus, Goldf. 

 Upper Jura ; Sontheiin, 

 Wurtemberg. 



Fia. 343. 



A, Sphaerites tabulatus, 

 Goldf. B, S. punctatus, 

 Goldf. Upper Jura; Streit- 

 berg, Franconia. 



A, Pentaceros iurassicus, Zitt. Upper Jura.; Bemfeld, near Ingol- 

 sta.lt, Bavaria. I/a- B, P. thoracifer, Gein. Planer ; Plauen, Saxony. 

 Marginal plate. C, P. primaevus, Zitt. Upper Jura ; Streitberg. 



conical spines (Fig. 342), and others are smooth or punctate (Fig. 343). 

 Their zoological position has not as yet been satisfactorily determined. 



VOL. I 



