NO. 5 RHYNCHONELLOID BRACHIOPODS — COOPER 1 5 



Family Cryptoporidae Muir-Wood, 1955. — Primitive rhyncho- 

 nelloidea having a large deltoid foramen slightly restricted by elongate, 

 triangular, elevated deltidial plates; crura long, maniculifer, continu- 

 ous with the socket ridges ; median septum strongly elevated ; cardinal 

 process a lobate thickening between the socket ridges ; one pair of 

 nephridia. 



Genera : Cryptopora and Mannia. 



Cryptopora, — Triangular in outline, exterior smooth. 



Mannia. — Exterior spinose, with spoon-shaped expansion of median septum 

 of brachial valve (validity of genus in question, see text, p. 22). 



Basiliolidae Cooper, new family. — Smooth or semicostate rhyn- 

 chonelloids having conjunct deltidial plates and small auriculate 

 foramen ; pedicle valve with dental plates varying from nearly obsolete 

 to strong, pedicle collar well developed ; brachial valve with broad 

 falcifer crura supported by outer hinge plates or the socket ridge; no 

 median septum but a median ridge may be present. 



Subfamilies : Basiliolinae, Aphelesiinae, and Aetheiinae. 



Basiliolinae Cooper, new subfamily. — Basiliolidae with crura at- 

 tached to broad outer hinge plates ; no median septum. 



Genera: Basiliola, Eohcmithyris, Neorhynchia, Rhytirhynchia, 

 Probolarina, and Streptaria. 



Basiliola. — Brachial valve much deeper than the pedicle valve ; pedicle collar 

 elaborate; exterior smooth; anterior commissure strongly uniplicate. 



Eohcmithyris. — Valves subequal in depth, smooth to semicostate ; anterior 

 commissure uniplicate. 



Neorhynchia. — Deltidial plates disjunct; exterior smooth but anterior commis- 

 sure sulcate; incipient inner hinge plates. 



Rhytirhynchia. — Outline like that of Basiliola but anteriorly costate; anterior 

 commissure sulciplicate. 



Probolarina. — Beak elongated ; deltidial plates well exposed ; anterior half 

 strongly costate ; elaborate pedicle collar ; anterior commissure uniplicate. 



Streptaria. — Exterior smooth to semicostate; anterior with sides twisted; 

 foramen with reflected rim; dental plates reduced; pedicle collar poorly 

 developed. 



Aphelesiinae Cooper, new subfamily. — Basiliolidae with crura at- 

 tached directly to side of socket ridge; thick median ridge present in 

 brachial valve. 



Genus: Aphelesia. 



Aphelesia. — Smooth to anteriorly costate ; anterior commissure uniplicate. 

 Aetheiinae Cooper, new subfamily. — Basiliolidae having a minute 



