CLASS I 



ECHINOIDEA 



289 



Echinoneus Leske. Amb narrow, actinally unequally broad, owing to the 

 obliquity of the large, triangular peristome. Miocene to Recent. 

 Caratonms Ag. Cretaceous. Amhlypygus Ag. Tertiary. 

 Fygaidus Ag. (Fig. 406). Test small, thick ; apical system slightly 



Fi(i. -106. 



ryiinnliis desmoulinsi Aj;'. Urj;'onian 

 (Schiattenkalk) ; Siiiitis, Switzerland, i/j. 



Fi(!. 40r. 



Pyrina iiiscia (Ag.). Ni'oeoiuian (Hils) ; Bwklingen, 



Brunswick. Vj. 



eccentric in front. Anhh narrow, widest at the ambitus ; pore-pairs in simple 

 series, conjugated ; the pores of a pair sometimes differently shaped. Cre- 

 taceous. 



Pyrina Desm. (Fig. 407).' Like the preceding, but pores non-conjugated, 

 and tlie pairs separated by costae. Cretaceous and Eocene. 



Subfamily B. Eghinobeissinae Duncan. 



Test depressed, elongate, tumid. Ambulacra suh-petaloid. Apical system and 

 peristome eccentric ; jloscelle absent or rudimentary. Interambulacra entering the 

 peristomal margin with a single plate. Periproct supra-marginal. 



Nmleolites Lam. {Echinohrissus Breyn.) (Fig. 408). Test ovate, rounded in 

 front, broadest and more or less truncated behind ; or rectangular, with the 



Fig. 40a' 



A, B, Niiclcolitus rluiui-idKri.s (Ijlhwyd). Cornbrash ; Egg, Aargau. Vi- ''. D, N. smtatas (Lani.). Upper 

 Oxfordiau ; Trouville, Calvados. C, Ventral aspect of large individual. D, Apical system, enlarged (after 

 Cotteau). 



angles rounded ; or sub-circular ; concave actinally. Amb unequal, open at 

 the end of the sub-petaloid parts ; pore-pairs in simple series, more or less 

 unequal in shape and size, the outer ones elongate ; below the sub-petaloid 

 parts the pores are in small oblique pairs, conjugate or not. Periproct at 

 upper end of a groove situated on the abactinal area of the test. Abundant 

 in Upper Jura and Cretaceous ; present also in Eocene and late Tertiary. 

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