koninckinid^ — strophomenid^. 327 



Family KONINCKINIDJE. 



Shell small, conccavo-convex ; hinge-margin straight or curved, 

 without area ; no foramen ; spiral lamellae with their apices 

 directed towards the large A'alve. 



KoNiNCKiNA, Suess, 1853. 



Did7\ — Triassic ; TJ. S. K. Leonha7^di, Wissm. (cxxxviii, 

 33-36). 



Shell orbicular, concavo-convex, smooth ; valves articulated ? 

 closely appressed ; ventral valve convex, dorsal concave ; beak 

 incurved, no hinge-area nor foramen ; interior of each valve 

 furrowed by two spiral lines of four volutions, directed inwards, 

 and crossing the vascular impressions ; umbo with three diverg- 

 ing ridges. The small spiral cavities, once occupied by the arms, 

 and now filled with spar, may be seen in specimens with both 

 valves, by holding them to the light. M. Suess, of Vienna, 

 states that he has found traces of very slender spiral lamellae 

 occupying the furrows. 



Anoplotheca, Sandberger, 1856. 



JDistr. — Devonian ; Europe. A. veniista, Schnur. 



Shell fibrous, concavo-convex, without foramen, area or del- 

 tidium ; hinge-margin curved ; large valve convex, with two teeth 

 and a median septum which is anteriorly cleft, and on either 

 side of which are the muscular impressions ; smaller valve hot 

 so deep, with cleft hinge-process, and close to it the lamellae, to 

 which the spirals were attached. 



Thecospira, Zugmaj^er, 1880. 



Didr. — Rhsetian. T. Haidingeri, Suess. 



Shell like Thecidium, but with spirals within, similar to those 

 of Koninckina, the axes diverging towards the large valve, the 

 bases roof-like over the small valve. 



Family STROPHOMENID^. 



Shell transversely oblong, depressed, rarel}' foraminated ; 

 hinge-line wide and straight ; beaks inconspicuous ; valves plano- 

 convex, or concavo-convex, each with a hinge-area notched in 

 the centre ; ventral valve with prominent teeth ; muscular impres- 

 sions occupying a saucer-shaped cavity with a raised margin ; 

 adductor central ; cardinal and pedicel impressions conjoined, 

 lateral, fan-like; dorsal valve with a tooth-like cardinal process 

 between two curved brachial processes ; adductor impression 

 quadruple; vascular impressions consisting of six principal 



