326 CAMBRIAN BRACHIOPODA. 



Subfamily EOOETHINiE Walcott [1908e, p. 148J. 



Derived Orthacea neariy always with large open delthyria; deltidia and chilidia occasion- 

 ally retained tliroughout life, but more often only in the younger-growth stages. Cardinal 

 process well developed. Shell structure dense, granular, and with punctate lamellae. 



Eoorihis Walcott [1908d, p. 102]. 



FinTcelnburgia Walcott [1905a, p. 277]. 



Superiamily STROPHOMENACEA Schuchert [1896, p. 312]. 



(Emended Schuchert [1897, p. 131] and Walcott [1908e, p. 148].) 



Derived, progressive, terminal Protremata, out of Orthacea (Billingsellidse) . Deltidia and 

 chilidia nearly always well developed. Cardinal process always well developed. 



Family STROPHOMENIDiE King [1846]. 



SubfamUy RAriNESQUIN.a: Schuchert [1893, p. 153]. 



(Emended Schuchert [1897, p. 132] and Walcott [1908e, p. 148].) 



Strophomenoids having generally a convex ventral and a concave or nearly flat dorsal 

 valve. 



Eostrophomena Walcott [1905a, p. 256]. 



Superfamlly PENTAMERACEA Schuchert [1896, p. 320]. 

 (Emended Schuchert [1897, p. 134] and Walcott [1908e, p. 148].) 



Specialized Protremata with well-developed free or supported spondylia and cruralia. 

 Deltidia and chilidia usually absent. 



Family STNTROPHIID.ffi Schuchert [1896, p. 320]. 

 (Emended Schuchert [1897, p. 135] and Walcott [1908e, p. 148].) 



Primitive Pentameracea with long, straight cardinal areas. 

 (?) Swantonia Walcott [1905a, p. 296]. 

 Syntrophia Hall and Clarke [1892c, p. 270]. 

 Huenella Walcott [1908d, p. 109]. 

 Olarlella Walcott [1908d, p. 110]. 



