288 ENALLASTER 



Genus. — Enallaster, d' Orbigny, 1853. 



Hemipneustes, Forbes, 1852 (non Agassiz, 1836). 

 ToxASTER, Roemer, 1850 (non Agassiz). 

 Enallastee, Be Loriol, 18/3. 



Test more or less cordiforrn. 



Ambulacral summit subcentral. 



Ambulacral pairs subpetaloidal, unequal, and depressed. 



Poriferous zones in the anterior pair unequal. The posterior zones are much larger 

 and wider than the anterior zones. In the small short pair of posterior ambulacra the 

 poriferous zones are equal. 



The anteal sulcus wide. Single ambulacrum, one third wider than the laterals, has 

 narrow poriferous zones, in which each pair of holes are set well spaced out and disposed 

 very oblique to each other ; a small tubercle rising from the surface of the partition wall 

 between the pores divides them, and developes an ornamental beaded line on each side of 

 the area. 



Apical disc small, compact, with four perforated ovarial and five perforated ocular 

 plates. 



Mouth near the anterior border. Peristome subpentagonal, with well-defined 

 margin. 



Vent in the middle of the truncated posterior border. Periprocte oval, with well- 

 defined margin. 



Enallaster Eittoni, Forbes, 1852. PI. LXV, figs. 1 a—/, 2 a — c. 



Hemipneustes Fittoni, Tories. Mem. Geol. Surv., decade iv, pi. v, note, 1852. 



— — Forbes. Morris. Catalogue of British Fossils, 2 ed., p. 82, 



1854. 

 Enallastek Fittoni, B6sor. Synopsis des Echinides fossiles, p. 357, pi. xl, figs. 



5—7. 1857. 



— — Jaccard. Jura Vaudois et Neucbatelois, p. 134, 1869. 



— — Be Loriol. Ecliin. Helv. Cretaces, t. ii, p. 359, pi. xxx, 



fig. 9, 1873. 



Diagnosis, — Test oval, cordiform, rounded and sinuous before, contracted behind. 



