235 



ORDER iv EUECHINOIDEA CLYPEASTROIDA 



rather flat actinally. Amb long, open, with broad poriferous zones nearly to 

 ambitus, narrowing thence to peristome. Pores wide apart and in pairs where 



Conodypeus conoideus, Goldf. sp. 



FIG. 378. 

 Eocene ; Kressenberg, Bavaria (2/ 3 natural size). 



the zones are broad ; the pairs separated by costae. Pores continued in single 

 series over the ambitus as far as the central, pentagonal peristome. Periproct 

 infra-marginal, oval (?). Cretaceous ; Eocene. 



Galeropygus, Cotteau ; Pachyclypeus, Desor. Upper Jura ; Europe. 



Order 4. CLYPEASTROIDA. Duncan. 



" Euechinoidea with an actinal peristome, a periproct situated beyond the dor so- 

 central system, in the posterior interambulacrum ; with external branchiae; with 

 tentacular pores in the interambulacra, and more than a pair to an ambulacral 

 plate; tentacles heteropodous in arrangement; with more or less horizontal and 

 rarely vertical teeth, and with jaws situated superiorly to the disconnected perignathic 

 girdle. Spheridia few, covered." Duncan. 



Family 1. Fibulariidae. Gray (emend. Duncan). 



Test small, with rudimentary, widely open, few-pored petals. Interambulacra 

 small, with a single apical and a single peristomial plate. Ambulacra limited 

 actinally on the interior of the test by low vertical partitions at ibtir sides, radiating 

 toward the peristome. Perignathic processes broad, low, one on each interambu- 

 lacrum. Periproct usually actinal. Cretaceous to Kecent. 



Echinocyamus, van Phels. Test thick, depressed, pyriform or sub-circular 

 in outline, concave actinally. Amb broader than the lAmb, short where 

 slightly petaloid, widely open distally ; pairs of pores few and increasingly 



