CLASS II 



BRACHIOPODA 



413 



converging and united with the median septum. Silurian to Lower Carboni- 

 ferous. Distribution general. 



(?) Cyrtinopsis Scupin. Like Cyrtina, but shell structure is not punctate. 

 Devonian ; Germany. 



Thecocyrtella Bittner. Very small, ventrally cemented, smooth-shelled 

 Cyrtinae. Alpine Trias. Cyrtotheca Bittner. Alpine Trias. 



BiUnerula Hall and Clarke. Like Thecocyrtella^ but with the abbreviated 



A, Cyrtina hcteroclyta(DefT.). Devonian ; Eifel. i/j. £, Shell with _ 



dorsal valv« mostly removed, showing spiralia, s/g (after Davidson). *^^'* ^^^' 



C, Cyrtina carhonaria M'Coy. Lower Carboniferous ; Kendal, Ireland. Spiriferina rostrata (Sowerby). 



i/i. Interior of ventral valve. The pseudodeltidium is removed to Middle Lias ; Ilminster. i/i (after 



show the dental plates and median septum. Davidson), 



dental plates uniting with the very high median septum, forming a transverse 

 platform beneath the united deltidial plates. Alpine Trias. 



Spiriferina d'Orb. (Fig. 625). Like Spirifer, but with the shell substance 

 punctate, and a prominent ventral median septum. Loop simple, complete. 

 Carboniferous to Jura. 



Suessia Deslongchamps. Similar to Spiriferina, but the dental plates not 

 extending to the bottom of the valve. Jugum with a median process. Jura ; 

 Europe. 



Family 5. Uncitidae Waagen. 



Spiriferacea with the crura directly continuous with the bases of the primary 

 lamellae. Spiralia laterally directed. Jugum as in Suessiidae. Just within the 

 posterior margin of the dorsal valve are concave pouch-like plates. 

 united and deeply concave. Shell structure impunctate, 

 Family anomalous. Devonian and Permian. 



Uncites Defrance (Fig. 626). Shells rostrate, striate, 

 with the ventral beak long, frequently distorted and 

 arched. No cardinal area. Deltidial plates united, 

 forming a concave plate. Pouch-like plates just within 

 the margins of the dorsal valve. Devonian ; Germany. 

 Uncinella Waagen. Permian ; India. 



Family 6. Rhynohospiridae Hall and Clarke. 



Derived Spiriferacea with the bases of the primary 

 lamellae situated between the spiralia and sharply recurved 

 dorsally at their junction with the crura. Spiralia laterally 

 directed. 



Deltidial plates 



Fio. 626. 



Uncites gryphus (Schloth.). 



Jugum usually with a Single process that is ?oSf 'i/f"'^''^' "'*' 



