CLASSIFICATION CAMBRIAN BRACIIIOPODA WALCOTT I45 



muscle scars prophetic of the Protremata. Derived out of Rus- 

 tellacea. 



Family KUTORGINID^. Schuchert, 1893 



Progressive transverse Kutorginacea with rudimentary cardinal 

 areas, great delthyrial opening, rudimentary articulation, and imma- 

 ture pseudodeltidia. Muscle scars prophetic of the Strophomenacea. 

 Ktitorgina 



Family SCHUCHERTINID^ Walcott, new 



Primitive round Kutorginacea with small cardinal areas. Exter- 

 nally like Obolus, with an open subtriangular delthyrium which 

 apparently is without a pseudodeltidium. Muscle scars and vascular 

 markings prophetic, through the Billingsellidse, of the Stropho- 

 menacea. 



Schuchertina 



Order NEOTREMATA Beecher, 1891 (emend) 



Derived and specialized inarticulate Brachiopoda (through the 

 Obolidas of the Atremata), as a rule more phosphatic than calcareous, 

 more or less cone-shaped, with the pedicle emerging during life 

 through a perforation or sheath in the ventral valve, or a triangular, 

 more or less open cleft, or only so in the youngest shelled stage, after 

 which the ventral valve becomes attached by a pedicle to foreign ob- 

 jects. Pedicle cleft in derived forms modified by a listrium. Pseudo- 

 deltidia and pseudochilidia as a rule not well developed. 



Superfamily SIPHONOTRETACEA Walcott and Schuchert, new 



Primitive, thick-shelled, calcareous or corneous, oboloid Neotre- 

 mata, with the pedicle passing through a ventral sheath, the aperture 

 •of which may remain apical and circular in outline, or it may become 

 elongate through resorption by passing anteriorly through the pro- 

 tegulum and umbo of the shell. A listrium is not developed. Dor- 

 sal protegulum marginal. 



Family OBOLELLID^ Walcott and Schuchert, new 



Primitive Siphonotretacea with the pedicle emerging through a 

 small circular perforation in the apex of the ventral valve, posterior 

 ito the protegulum. Derived out of the Obolidae. 

 Obolella 



(Glyptias) 

 Botsfordia 

 Schizopholis 

 ( ?) Quehecia 



