ECIIINOID GENUS ECHINOCOIÎYS

GENUS ECHINOCORYS IN THE SENONIAN OF BELGIUM
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DESCRIPTIONS.
Class Echinoidea d'Orbigny 1851.
SUBCLASS ATELOSTOMATA POMEL 1869.
Peristome deprived of jaws, or with only imperfect or temporary ones.
ORDER NODOSTOMATA LAMBERT 1912.
Peristome completely lacking jaws.
SUBORDER SPATANGOIDEA AGASSIZ 1840.
Test bilateral, peristome variable, often labiate but always without phyllodcs;
plates of posterior interambulacrum developing a plastron on ventral surface;
periproct without contact Avith the apex in the adult.
Family ANANCHITIDAE A. Gras 1848.
Apex elongate, plastron meridosterne; ambulacra not petaloid, or only subpel
aloid.
Subfamily Holasteridae Lambert 1917.
Ambulacra composed of biporiferous plates.
TRIBE ECHINOCORINAE LAMBERT 1917.
Test ovoid; peristome reniform; homogeneous ambulacra; periproct
marginal.
infra
GENUS ECHINOCORYS BREYNIUS 1732.
Test ovoid, without trace of anterior groove; ambulacra similar and formed
of variable type pores in certain different groups; elongation of the apex variable;
periproct almost always a narrow pointed oval, varying in position from near
marginal to inframarginal and ventral.