486 THE PALEONTOLOGY OF MINNESOTA. 
(Classification of paleozoic Lamellibranchiata. 
Family CYPRICARDINIIDAS, (Provisional.) 
GENUS: Cypricardinia, Hall. 
Family CYRTODONTIDA, Ulrich. 
GENERA: ? Cypricardites, Conrad; Cyrtodonta, Billings; Ischyrodonta, Ulrich; Matheria, Billings; Ortonella, 
Ulrich. ? Ptychodesma, Hall; Vanuxemia, billings; Whitella, Ulrich. 
Suborder HOMOMYARIA. 
Mantle lobes either separate or united posteriorly. The two adductor muscles of nearly equal 
strength. 
Family ARCIDA, Lamarck. 
GENERA: Carbonarca, Meek and Worthen; Macrodon, Lycett; Nyassa, Hall; ? Spenotus, Hall. 
Family PARARCID®, (Provisional). 
GENERA: Cardiola, Broderip; Cardiopsis, Meek and Worthen; Dewxiobia, Winchell; Glyptocardia, Gall; 
Lunulicardium, Miinster; Oreecardium, Herrick: Panenka, Barrande; Paracardium, Hall; 
Pararca, Hall. 
Family NUCULIDA, Gray. 
GENERA: ? Clidophorus, Hall; Ctenodonta, Salter (Tellinomya, Hall); @oniodon, Herrick; Nucula, Lam- 
arck; Nuculana, Link; Nueulites, Conrad; Paleoneilo, Hall; ? Pyrenomceus, Hall; Yoldia, 
Moller. 
Family LYRODESMIDA, Ulrich. 
GENERA: Allodesma, Ulrich; Ischyrina, Billings; Lyrodesma, Conrad; Technophorus, Miller. 
Family TRIGONIDAS, Lamarck. 
GENERA: ? Cytherodon, Hall; ? Schizodus, King. 
Family UNIONIDAL 
GENERA: ? Amnigenia, Hall; ? Anthracosia, King; Prisconaia, Conrad. 
? 
Family ELYMELLIDAS, (Provisional). 
GENERA: Elymella, Hall; Glossites, Hall. 
Order SIPHONIDA, Woodward. 
Mantle lobes more or less united; siphons of varying lengths, either separate or united, are 
developed; both adductor muscles well developed. 
Family SOLENOMYIDA®, Gray. 
GENERA: Solenomya, Lamarck; Clinopistha, Meek and Worthen; Phthonia, Hall. 
Family SANGUINOLITID®, Miller. 
GENERA: Promacrus, Meek; Sanguinolites, McCoy. 
