The writer bases classification of the Hexactinosa on the methods used by Ijima, and does not follow the views of Schrammen or de Laubenfels. Suborders Clavularia Schulze and Scopularia Schulze are characterized in modern examples by the presence of clavules and scopules respectively; these loose microscleres are lacking in fossil material, but correlated skeletal differences can be used as alternative criteria. Beyond this, the desirable basis of familial classification is that each family distinguished should include all genera agreeing in a) the fundamental structure of the dictyonal framework, and b) the type of canal system and/or skeletal canalization developed, unless grounds exist for regarding resemblances in (b) as reflecting parallel developments.

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