152 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



Subfamily TORYNECHINAE Grant n. subfam. 



Uncinuliform Stenoscismatidae with stolidium greatly reduced (or 

 absent) ; costae at beaks. 



Genus TORYNECHUS Cooper and Grant 1962 



Uncinuloides KING, R.E., 1931, Univ. Texas Bull. 3042, p. 112 (part). 

 Torynechus COOPER, G. A. and GRANT, R. E., 1962, Journ. Paleontology, 

 vol. 36, No. 5, p. 1128. 



Shell uncinuliform; transversely subtrigonal to subpentagonal ; 

 commissure uniplicate, fold and sulcus with low relief ; edges of valves 

 slightly protruding to form rudimentary stolidium ; anterior and ante- 

 rolateral surfaces flattened, with each costa there deeply grooved; 

 costae fine, numerous, sharp or blunt, beginning at beaks, added ante- 

 riorly by intercalation or bifurcation, producing shallow serration of 

 commissure ; concentric ornamentation fine, closely spaced. 



Pedicle valve moderately convex; beak rather long, attenuate, 

 slightly hooked ; beak ridges blunt, not obvious ; delthyrium triangular, 

 constricted by small deltidial plates ; flanks may be slightly reflexed ; 

 lateral valve edges covered by edges of brachial valve ; anterior margin 

 abruptly bent to meet levigate surface. 



Brachial valve more strongly convex except along crest of fold; 

 beak somewhat swollen, slightly attenuate ; anterior edge sharply bent 

 toward commissure. 



Pedicle valve interior with one small hinge tooth fused to each side ; 

 dental plates large, converging on or just above floor of valve, forming 

 elongate, boat-shaped spondylium and low, supporting median septum : 

 space between floor and spondylium may be filled by callus, envelop- 

 ing septum. Muscle marks in anterior two-thirds of spondylium, faint 

 and undifferentiated ; pallial marks on floor of valve ; gonocoels form- 

 ing deep straight troughs, slanting slightly backward from edge of me- 

 dian septum and weakly texturing posterior valve floor ; vascula media 

 producing two slightly raised trunks, diverging forward from edge of 

 median septum, each splitting nearby to produce lateral and anterior 

 branches, each branch bifurcating at least once, splitting again at ex- 

 tremities, sending slender apophyses to edge of valve. 



Brachial valve interior with large, subtrigonal to crescentic hinge 

 plate greatly thickened at apex of valve to form large cardinal process, 

 striate or serrate radially for attachment of diductor muscles ; hinge 

 sockets at lateral extremities of hinge plate, wide, deep, short, coarsely 

 denticulate ; crural bases diverging forward from near base of cardinal 

 process, space between them filled by callus or extension of cardinal 

 process or short crural plate, uniting with top of intercamarophorial 

 plate ; crural processes extending free into living chamber, conforming 



