CLASS II 



BRACHIOPODA 



391 



Froboscidella CEhlert. Valves very unequal ; dorsal valve small, concave, 

 operculiform ; ventral valve larger, convex, furnished with two lateral expan- 

 sions which bend downward to meet the margins of the dorsal valve, and an 

 anterior expansion, which is produced forward into one, or occasionally two, 

 long cylindrical tubes. Carboniferous ; Europe and North America. 





Pig. 581. 



Sfrophalosia goldfussi (Miinst.). Permian ; Gera, Germany. A, 

 Dorsal aspect. P>, Profile. C, Interior of dorsal valve with brachial 

 impressions. Natural size. 



Subfamily C. Strophalosiinae, novum. 

 Prodxbdids anchored to foreign objects by the spines or by most of the ventral shell. 



Chonopectxis Hall and Clarke. Chonetes-\\\iQ shells, but cemented ventrally 

 to extraneous objects. External surface reticulated by a double, oblique 

 series of concentric lines and fine radiating striae. Lower Carboniferous ; 

 North America. 



Sfrophalosia King (Orthothrix Geinitz ; Leptaenalosia King) (Fig. 581). 

 Shell productoid in general 4 b c 



form, cemented by the ven- ,^4^^^ ('~"v 



tral umbo. Both valves .v<^&J"'~iz-a.. I \ 



with well-defined area, del- 

 tidium and chilidium. Ven- 

 tral valve with two pro- 

 minent teeth unsupported 

 by dental plates. Miiscular 

 impressions small ; brachial 

 ridges distinct. Surface of 

 ventral valve covered with 

 spines ; that of the dorsal 



valve either spinous, lamellose or smooth. Middle Devonian to Permian ; 

 Europe, India, North and South America. 



Aulosteges Helmersen. Much like Sfrophalosia, but not cemented by the 

 ventral umbo ; deltidium covered with small spinules and the surface of both 

 valves thickly set with spines. Permian ; Russia and India. 



Etheridgina CEhlert. Shell very small, nearly as broad as long, and 

 attached to foreign bodies, notably crinoid stems, by the spines of the ventral 

 valve. Dorsal valve with a small beak ; surface ornamented 

 by concentric fiexuous plications bearing a few scattered 

 spines. Carboniferous; Scotland. 



Family 4 Richthofeniidae Waagen. 



Strophomenacea developed out of the Froductidae, and 

 remarkably modified by ventral cementation. The form is that 

 of cyathophylloid corals with an operculiform dorsal valve. 

 Shell strihcture cysfose. Upper Carboniferous and Permian. 



Tegnlifera Schellwien. A youthful expression of the 

 highly modified Eichthofenia, in which the productoid 

 characters are still recognisable. Upper Carboniferous ; 

 Austria. 



Fiichthofenia Kayser (Fig. 582). These most remarkably 



Pig. 582. 



Richthofenia lawrenci- 

 ana Waagen. Permo-Car- 

 boniferoiis ; Salt Range. 

 Vertical section of ven- 

 tral valve (after Waagen). 



