220 PEor. p. M. DTJisrcAisi s eevision of the 



open, and the pairs of pores of the anterior zones smaller than 

 those of the posterior. 



Interradia tumid, the right posterior interradium actinally 

 with normal heterouomy, the plates 2 and 3 of zone a being 

 united ; a sternum not quite symmetrical, but still amphisternous, 

 and no true episternum. 



Peristome excentric in front, subcircular or pentagonal, trans- 

 verse ; a small posterior labrum. Periproct in the posterior 

 truncation. Tubercles distinct, small. 



Fossil. Cretaceous : England, Europe, IS". Africa, Asia (Syria). 



De Loriol has proved the identity of Ennalaster and lELeteraster. 



Genus Ennalaster, d'Orbigny, 1853, PaZ. Frang. vi. Terr. Gret. 

 EcJi. p. 181. JDe Loriol, 1884, Bee. Zool. Suisse, i. no. 4, 

 p. 622; 1888, Faune Gret. du Portug., EcJi. ii. fasc. 2, 

 pp. 87-92, pis. xvi. & xvii. 



Syn. Seteraster, d'Orb. 1853. 



Test of small or moderate size, cordiform, low, tumid, slightly 

 longer than broad, grooved in front, truncated behind. 



Apical system compact, coinciding variably with the apex, 

 may be excentric ; four basal plates ; the madreporite large, and 

 separating or not the posterior basal plates. 



The ambulacra diverse, the anterior broad in the slight anterior 

 groove of the test, the broad pairs of pores close in vertical suc- 

 cession, numerous, a larger pair alternating with a small pair ; 

 the outer row of pores of the larger pairs elongate, and the 

 inner smaller and shorter ; intermediate small pairs either with 

 elongate or circular outer pores, but always smaller than the 

 others. 



Petaloid parts of the antero-lateral ambulacra divergent, 

 flexuous, tending to close, nearly flush, the poriferous zones un- 

 equal, the posterior the largest, anterior zone may be small ; 

 postero-lateral ambulacra short, divergent, zones unequal or not. 



Peristome excentric in front, labiate, wide, arched in front. 

 Periproct in the posterior truncation. 



There are no fascicles. 



Fossil. Cretaceous ; England, Europe, IN". Africa, Asia (Syria). 



A careful comparison of the species of Echinospatagus and 

 Fnnalaster leaves great doubts in the mind whether the dif- 



