KONINCKINIDA—STROPHOMENIDZ. 327 
Famity KONINCKINID A. 
Shell small, concavo-convex; hinge-margin straight or curved, 
without area; no foramen; spiral lamelle with their apices 
directed towards the large valve. 
KOoNINCKINA, Suess, 1853. 
Disir.—Triassic; U. 8S. K. Leonhardi, Wissm. (cexxxviil, 
393-36). 
Shell orbicular, concayo-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, 
aud crossing the vascular impressions ; uimbo 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 lamellee 
occupying the furrows. 
ANOPLOTHECA, Sandberger, 1856. 
Distr.—Devonian; Europe. A. venusta, 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 not 
so deep, with cleft hinge-process, and close to it the lamellz, to 
which the spirals were attached. 
TuHeEcospirA, Zugmayer, 1880. 
Distr.—Rhetian. TJ. 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. 
Famity STROPHOMENID 4. 
Shell transversely oblong, depressed, rarely 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 
